Fusion proteins targeting tumour associated macrophages for treating cancer

ABSTRACT

The present invention relates to cancer immunotherapy. In particular, provided herein are fusion proteins for targeting tumor associated macrophages with immunostimulatory agents.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 16/085,126, filed Sep. 14, 2018, allowed as U.S. Pat. No. 11,186,641, is a Section 371 U.S. national stage entry of International Patent Application No. PCT/IB2017/000388, International Filing Date Mar. 16, 2017, which claims the benefit of U.S. Provisional Application Ser. No. 62/309,704, filed Mar. 17, 2016, which are incorporated herein by reference in their entireties.

SEQUENCE LISTING

The text of the computer readable sequence listing filed herewith, titled “34589-303_ST25”, created Nov. 16, 2021, having a file size of 188,000 bytes, is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to cancer immunotherapy. In particular, provided herein are fusion proteins for targeting tumor associated macrophages with immunostimulatory agents.

BACKGROUND OF THE INVENTION

Despite advances in our understanding and management of cancer, the majority of cancer patients will still die of the disease. For many patient groups, prognosis is dire, with few or no available curative treatment regimens. Furthermore, resistance development and disease relapse is commonplace. There is therefore an unmet need for the development of novel therapeutics founded on fundamentally different mechanisms of action.

The ability of the immune system to fight cancer has been clearly demonstrated in recent years, highlighted by the massive clinical and commercial success of the immune checkpoint inhibitors. One of the key advantages offered by these drugs is that they have the potential to treat several cancer types and are supplied in an off-the-shelf manner. In contrast to personalized immunotherapies such as adoptive T-cell therapy or dendritic cell (DC) vaccines, they do not rely on customization for each patient. On the downside, only 10-30% of patients respond adequately, and checkpoint inhibitors have a challenging safety profile.

Tumor Associated Macrophages (TAMs) represent up to 50% of the tumor mass. TAMs constitute an extremely heterogeneous population; they originate from blood monocytes, which differentiate into distinct macrophage types, schematically identified as M1 (or classically activated) and M2 (or alternatively activated). It is now generally accepted that TAM have an M2 phenotype and show mostly pro-tumoral functions, promoting tumor cell survival, proliferation, and dissemination. High levels of TAM are often, although not always, correlated

with a bad prognosis, and recent studies have also highlighted a link between their abundance and the process of metastasis. This pathological evidence has been confirmed also at gene level, where molecular signatures associated with poor prognosis in lymphomas and breast carcinomas include genes characteristic of macrophages.

What is needed in the art are additional agents and methods that can be used to treat many different types of cancer and tumors.

SUMMARY OF THE INVENTION

The present invention relates to cancer immunotherapy. In particular, provided herein are fusion proteins for targeting tumor associated macrophages with immunostimulatory agents.

For example, in some embodiments, the present invention provides a fusion protein, comprising an immunostimulatory agent (e.g., IL15 polypeptide or fragment thereof) fused to a targeting unit that targets the immunostimulatory agent to a tumor associated macrophage. In some embodiments, the targeting unit binds to CD206. In some embodiments, targeting unit is an immunoglobulin or fragment thereof that specifically binds to CD206. In some embodiments, the immunoglobulin is a single domain antibody (sdAb) or a single chain variable fragments (scFv), although other antibodies or antibody fragments are specifically contemplated. In some embodiments, the immunostimulatory agent is the sushi domain of IL15 receptor alpha (IL15ra-sushi). In some embodiments, a CD206 specific sdAb is fused to the IL15ra-sushi via a linker to serve as the therapeutic molecule 206RLI. The present invention is not limited to particular immunostimulatory agents. Examples include, but are not limited to, cytokines (e.g., interferon alpha, interferon gamma, interleukin-21, interleukin-17, interleukin-18, interleukin-27, TNF-α, interleukin 2, interleukin 7, interleukin 12); co-stimulatory ligands (e.g., 41bb, CD80, CD86); and antibody fragments with agonistic or antagonistic activity against immune checkpoints (e.g., anti-PD1, anti-CTLA4, etc). The present invention is not limited to particular targeting units or targets. Examples include, but are not limited to, mannose receptor (CD206), folate receptor beta (FOLR2) and leugmain (LGMN).

Accordingly, in some embodiments, the targeting unit binds to a protein selected from the group consisting CD206, FOLR2, LGMN, CD204, CD163, and CD301. In some embodiments, the targeting unit is an antigen binding protein that specifically binds to the CD206. In some embodiments, the antigen binding protein is selected from the group consisting of an immunoglobulin single variable domain and a single chain variable fragment (scFv). In some embodiments, the immunoglobulin single variable domain is a nanobody. In some embodiments, the nanobody binds to CD206. In some embodiments, the nanobody is selected from the group consisting of nanobodies having an amino acid sequence selected from the group consisting of SEQ ID NOs: SEQ ID NOs: 30-56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, and 112 and nanobodies that have at least 80% identity to the sequences. In some embodiments, the nanobody has a CDR1, CDR2 and/or CDR3 or a variant thereof from the list of CDRs for nanobodies that bind CD206 in Table 1. In some embodiments, the immunoglobulin single variable domain binds to FOLR2. In some embodiments, the immunoglobulin single variable domain has an amino acid sequence selected from the group consisting of SEQ ID NO: 122 and single domain antibody fragments that have at least 80% identity to the sequence. In some embodiments, the nanobody has a CDR1, CDR2 and/or CDR3 or a variant thereof from the list of CDRs for nanobodies that bind FOLR2 in Table 1.

In some embodiments, the immunostimulatory agent is selected from the group consisting of an interleukin, an interferon and a tumor necrosis factor. In some embodiments, the interleukin is selected from the group consisting of IL-10, IL-2, IL-7, IL-8, IL-12, IL-15, IL-17, IL-18, IL-21, IL-23, IL-27 and IL-33. In some embodiments, the interleukin is selected from the group consisting of an IL15 polypeptide, IL15 alpha receptor or fragment or fusion thereof. In some embodiments, the interferon is selected from the group consisting of IL-10, IL-2, IL-7, IL-8, IL-12, IL-15, IL-17, IL-18, IL-21, IL-23, IL-27 and IL-33. In some embodiments, the tumor necrosis factor is selected from the group consisting of CD40L, EDA, FASL, LTA, LTB, RANKL, OX40L, TNF, TNFSF7, TNFSF8, TNFSF9, TNFSF12, TNFSF13, TNFSF13B, F18, TRAIL, BAFF, 4-1BBL, and 4-1BB.

In some embodiments, the targeting unit and the immunostimulatory agent are connected by a linker. In some embodiments, the linker has an amino acid sequence selected from the group consisting of SEQ ID NO:109, SEQ ID NO:110 and SEQ ID NO:147.

In some embodiments, the fusion protein has an amino acid sequence encoded by a nucleic acid sequence selected from the group consisting of SEQ ID NOs:1, 138-146 and 153-170 and sequences having at least 80% identity to the amino acid sequences.

Further embodiments provide a nucleic acid encoding the fusion protein and vectors comprising the nucleic acid.

Still further embodiments provide a pharmaceutical composition comprising the fusion protein described herein. In some embodiments, the pharmaceutical composition further comprise at least one of a pharmaceutically acceptable carrier, adjuvant, or diluent.

In some embodiments, the present invention provides antigen binding proteins comprising a CDR1, CDR2 and/or CDR3 and CDRs having at least 80% identity to the CDR1, CDR2, and/or CDR3 from an immunoglobulin single variable domain amino acid sequence that binds to CD206 or FOLR2 as identified in Table 1. In some embodiments, the antigen binding protein binds to CD206. In some embodiments, the antigen binding protein binds to FOLR2.

In some embodiments, the antigen binding protein is selected from the group consisting of an immunoglobulin or fragment thereof, a humanized immunoglobulin or fragment thereof, a single chain antibody (scFV), and an immunoglobulin single variable domain. In some embodiments, the antigen binding protein is an immunoglobulin single variable domain. In some embodiments, the immunoglobulin single variable domain is derived from a camelid antibody. In some embodiments, the immunoglobulin single variable domain comprises a nanobody sequence (V_(H)H).

In some embodiments, the immunoglobulin single variable domain has an amino acid sequence selected from the group consisting of SEQ ID NOs: 30-56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, and 108 and sequences having at least 80% identity to the sequences. In some embodiments, the immunoglobulin single variable domain comprises an amino acid sequence that comprises 4 framework regions (FR) and 3 complementarity determining regions (CDR) according to the following formula (1): FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4 (1); or any suitable fragment thereof.

In some embodiments, the antigen binding protein is fused to a moiety selected from the group consisting of an immunostimulatory agent, a toxin, a cytotoxic drug, an enzyme capable of converting a prodrug into a cytotoxic drug, a radionuclide, a cytotoxic cell; and wherein the domain is fused to the moiety directly or through a linker. In some embodiments, the antigen binding protein is fused, either directly or through a linker, to a detectable label.

In some embodiments, the present invention provides a nucleic acid encoding the antigen binding protein or fusion as described above. In some embodiments, the present invention provides a vector comprising the described nucleic acid sequences. In some embodiments, the present invention provides a pharmaceutical composition comprising the antigen binding protein or fusion as described above. In some embodiments, the pharmaceutical compositions further comprise at least one of a pharmaceutically acceptable carrier, adjuvant, or diluent.

Additional embodiments provide a methods of inducing a cancer specific immune response, comprising: administering a fusion protein as described herein to a subject diagnosed with cancer under conditions such that the subject generates or amplifies a pre-existing immune response to cancer cells in the subject. In some embodiments, the cancer is, for example, lung cancer, breast cancer, pancreatic cancer, prostate cancer, melanoma or multiple myeloma. In some embodiments, the immune response kills the cancer cells. In some embodiments, the immune response results in tumor regression.

Yet other embodiments provide a method of treating cancer, comprising: administering a fusion protein as described herein to a subject diagnosed with cancer under conditions such that the cancer is reduced or eliminated. In some embodiments, the subject generates an immune response to the cancer. In some embodiments, the conditions such that the cancer is reduced or eliminated comprise regression of a tumor. In some embodiments, the cancer is selected from the group consisting of lung cancer, breast cancer, pancreatic cancer, prostate cancer, melanoma and multiple myeloma.

Still further embodiments provide the use of the fusion proteins described herein to generate a cancer specific immune response in a subject. In some embodiments, the cancer is, for example, lung cancer, breast cancer, pancreatic cancer, prostate cancer, melanoma or multiple myeloma. In some embodiments, the immune response kills the cancer cells. In some embodiments, the immune response results in tumor regression.

In some embodiments, the present invention provides the use of the fusion proteins described herein to treat cancer in a subject. In some embodiments, the subject generates an immune response to the cancer. In some embodiments, the conditions such that the cancer is reduced or eliminated comprise regression of a tumor. In some embodiments, the cancer is selected from the group consisting of lung cancer, breast cancer, pancreatic cancer, prostate cancer, melanoma and multiple myeloma.

Additional embodiments are described herein.

DESCRIPTION OF THE DRAWINGS

FIG. 1A-B. Schematic overview of exemplary fusion proteins. FIG. 1A. An engineered protein comprising a targeting unit (an antibody fragment) connected to an immunostimulatory cytokine (interleukin 15; IL15) through a flexible linker. FIG. 1B. Schematic overview of a typical tumor, where cancer cells are embedded in a network of supporting cells and blood vessels. The targeting unit of the protein binds to a surface structure (CD206) that is expressed on a class of cells; tumor-associated macrophages (TAMs), which are abundantly present within tumors in most types of human cancer. Administration of the fusion protein results in specific binding to the cell surface of these cells. This leads to accumulation of IL15 within the tumor, which serves to activate tumor-infiltrating immune cells (T-cells and NK cells) to kill cancer cells.

FIG. 2A. An SDS-PAGE gel showing crude 206RLI product of the expected size (38 kDa) produced by this approach is shown in the right.

FIG. 2B. Flow cytometry verification of binding of the purified 206RLI compound to cells engineered to express human CD206 (blue), showing negligible binding to control cells (red). C. T cell proliferation assay showing the ability of purified 206RLI to stimulate growth of human CD4+ T cells isolated from blood of healthy donors. Of note, biological activity is found to be superior to that of recombinant interleukin 15 (rhIL15)

FIG. 3A. 206RLI treatment leads to the formation of a central necrotic ulceration within the tumors within a few days, and a rapid and dramatic shrinkage of tumors.

FIG. 3B. By day +10, the tumor bed is reduced to a dense scar tissue in the majority of the mice.

FIG. 4. Western blot using an anti-IL15 mAb.

FIG. 5. Results from flow cytometry using an APC-conjugated anti-IL15 antibody.

FIG. 6. Results of a CTLL-2 proliferation assay.

FIG. 7. presents results showing that the proliferation-inducing function of the 206Nb-hIL15 fusion protein fusion protein was superior to that of rhIL15 when used in CTLL-2 assays.

FIG. 8. Western blot using an anti-IL2 mAb.

FIG. 9. Results showing that the proliferation inducing effects of a 206Nb-hIL2 fusion protein exceed that of rh112 in a CTLL-2 assay.

FIG. 10. Protein gel demonstrating purification of a CL10scFv-IL15RLI fusion protein.

FIG. 11. Results of flow cytometry showing binding of the CL10scFv-IL15RLI fusion protein to mFOLR2-expressing NS0 cells.

FIG. 12. Results of flow cytometry using the 206Nb-RLI fusion protein to stain IL-4-treated, M2-like macrophages.

FIG. 13. Flow cytometry results showing preferential binding of FOLR2-RLI compared to the Ly6GNegLy6CNeg fraction and CD11bNeg cells, consistent with reactivity of the fusion protein against tumor-associated macrophages.

Definitions

As used herein, the term “subject” refers to any animal (e.g., a mammal), including, but not limited to, humans, non-human primates, rodents, and the like, which is to be the recipient of a particular treatment. Typically, the terms “subject” and “patient” are used interchangeably herein in reference to a human subject.

As used herein, the term “subject suspected of having cancer” refers to a subject that presents one or more symptoms indicative of a cancer (e.g., a noticeable lump or mass) or is being screened for a cancer (e.g., during a routine physical). A subject suspected of having cancer may also have one or more risk factors. A subject suspected of having cancer has generally not been tested for cancer. However, a “subject suspected of having cancer” encompasses an individual who has received a preliminary diagnosis (e.g., a CT scan showing a mass) but for whom a confirmatory test (e.g., biopsy and/or histology) has not been done or for whom the stage of cancer is not known. The term further includes people who once had cancer (e.g., an individual in remission). A “subject suspected of having cancer” is sometimes diagnosed with cancer and is sometimes found to not have cancer.

As used herein, the term “subject diagnosed with a cancer” refers to a subject who has been tested and found to have cancerous cells. The cancer may be diagnosed using any suitable method, including but not limited to, biopsy, x-ray, blood test, and the diagnostic methods of the present invention. A “preliminary diagnosis” is one based only on visual (e.g., CT scan or the presence of a lump) and/or molecular screening tests.

As used herein, the term “initial diagnosis” refers to a test result of initial cancer diagnosis that reveals the presence or absence of cancerous cells (e.g., using a biopsy and histology).

As used herein, the term “characterizing cancer in subject” refers to the identification of one or more properties of a cancer sample in a subject, including but not limited to, the presence of benign, pre-cancerous or cancerous tissue and the stage of the cancer.

As used herein, the term “stage of cancer” refers to a qualitative or quantitative assessment of the level of advancement of a cancer. Criteria used to determine the stage of a cancer include, but are not limited to, the size of the tumor, whether the tumor has spread to other parts of the body and where the cancer has spread (e.g., within the same organ or region of the body or to another organ).

Staging of cancer can also be based on the revised criteria of TNM staging by the American Joint Committee for Cancer (AJCC) published in 1988. Staging is the process of describing the extent to which cancer has spread from the site of its origin. It is used to assess a patient's prognosis and to determine the choice of therapy. The stage of a cancer is determined by the size and location in the body of the primary tumor, and whether it has spread to other areas of the body. Staging involves using the letters T, N and M to assess tumors by the size of the primary tumor (T); the degree to which regional lymph nodes (N) are involved; and the absence or presence of distant metastases (M)—cancer that has spread from the original (primary) tumor to distant organs or distant lymph nodes. Each of these categories is further classified with a number 1 through 4 to give the total stage. Once the T, N and M are determined, a “stage” of I, II, III or IV is assigned. Stage I cancers are small, localized and usually curable. Stage II and III cancers typically are locally advanced and/or have spread to local lymph nodes. Stage IV cancers usually are metastatic (have spread to distant parts of the body) and generally are considered inoperable.

As used herein, the term “characterizing tissue in a subject” refers to the identification of one or more properties of a tissue sample (e.g., including but not limited to, the presence of cancerous tissue, the presence of pre-cancerous tissue that is likely to become cancerous, and the presence of cancerous tissue that is likely to metastasize).

As used herein, the term “providing a prognosis” refers to providing information regarding the impact of the presence of cancer (e.g., as determined by the diagnostic methods of the present invention) on a subject's future health (e.g., expected morbidity or mortality, the likelihood of getting cancer, and the risk of metastasis).

As used herein, the term “non-human animals” refers to all non-human animals including, but not limited to, vertebrates such as rodents, non-human primates, ovines, bovines, ruminants, lagomorphs, porcines, caprines, equines, canines, felines, ayes, etc.

As used herein, the term “cell culture” refers to any in vitro culture of cells. Included within this term are continuous cell lines (e.g., with an immortal phenotype), primary cell cultures, transformed cell lines, finite cell lines (e.g., non-transformed cells), and any other cell population maintained in vitro.

As used herein, the term “eukaryote” refers to organisms distinguishable from “prokaryotes.” It is intended that the term encompass all organisms with cells that exhibit the usual characteristics of eukaryotes, such as the presence of a true nucleus bounded by a nuclear membrane, within which lie the chromosomes, the presence of membrane-bound organelles, and other characteristics commonly observed in eukaryotic organisms. Thus, the term includes, but is not limited to such organisms as fungi, protozoa, and animals (e.g., humans).

As used herein, the term “in vitro” refers to an artificial environment and to processes or reactions that occur within an artificial environment. In vitro environments can consist of, but are not limited to, test tubes and cell culture. The term “in vivo” refers to the natural environment (e.g., an animal or a cell) and to processes or reaction that occur within a natural environment.

The terms “test compound” and “candidate compound” refer to any chemical entity, pharmaceutical, drug, and the like that is a candidate for use to treat or prevent a disease, illness, sickness, or disorder of bodily function (e.g., cancer). Test compounds comprise both known and potential therapeutic compounds. A test compound can be determined to be therapeutic by screening using the screening methods of the present invention.

As used herein, the term “sample” is used in its broadest sense. In one sense, it is meant to include a specimen or culture obtained from any source, as well as biological and environmental samples. Biological samples may be obtained from animals (including humans) and encompass fluids, solids, tissues, and gases. Biological samples include blood products, such as plasma, serum and the like. Environmental samples include environmental material such as surface matter, soil, water, and industrial samples. Such examples are not however to be construed as limiting the sample types applicable to the present invention.

As used herein, the term “co-administration” refers to the administration of at least two agent(s) (e.g., a composition described herein and a chemotherapeutic agent) or therapies to a subject. In some embodiments, the co-administration of two or more agents/therapies is concurrent. In other embodiments, a first agent/therapy is administered prior to a second agent/therapy. The appropriate dosage for co-administration can be readily determined by one skilled in the art. In some embodiments, when agents/therapies are co-administered, the respective agents/therapies are administered at lower dosages than appropriate for their administration alone. Thus, co-administration is especially desirable in embodiments where the co-administration of the agents/therapies lowers the requisite dosage of a known potentially harmful (e.g., toxic) agent(s).

As used herein, the term “pharmaceutical composition” refers to the combination of an active agent with a carrier, inert or active, making the composition especially suitable for diagnostic or therapeutic use in vivo, in vivo or ex vivo.

As used herein, the term “pharmaceutically acceptable carrier” refers to any of the standard pharmaceutical carriers, such as a phosphate buffered saline solution, water, emulsions (e.g., such as an oil/water or water/oil emulsions), and various types of wetting agents. The compositions also can include stabilizers and preservatives. For examples of carriers, stabilizers and adjuvants. (See e.g., Martin, Remington's Pharmaceutical Sciences, 15th Ed., Mack Publ. Co., Easton, Pa. [1975]).

As used herein, the term “antigen binding agent (e.g., “antigen-binding protein” or protein mimetic such as an apatamer) refers to proteins that bind to a specific antigen. “Antigen-binding proteins” include, but are not limited to, immunoglobulins, including polyclonal, monoclonal, chimeric, single chain, single domain, and humanized antibodies, Fab fragments, F(ab′)2 fragments, and Fab expression libraries. Various procedures known in the art are used for the production of polyclonal antibodies. For the production of antibody, various host animals can be immunized by injection with the peptide or protein containing the desired epitope including but not limited to rabbits, mice, rats, sheep, goats, llamas, alpacas, etc. In a preferred embodiment, the peptide is conjugated to an immunogenic carrier (e.g., diphtheria toxoid, bovine serum albumin (BSA), or keyhole limpet hemocyanin (KLH)). Various adjuvants are used to increase the immunological response, depending on the host species, including but not limited to Freund's (complete and incomplete), mineral gels such as aluminum hydroxide, surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanins, dinitrophenol, Gerbu adjuvant and potentially useful human adjuvants such as BCG (Bacille Calmette-Guerin) and Corynebacterium parvum.

As used herein, the term “Tumor Associated Macrophage” or “TAM” refers to cells of macrophage lineage that are found in close proximity to or within tumor masses.

As used herein, the term “targeting unit that targets the immunostimulatory agent to a tumor associated macrophage” refers to a targeting unit (e.g., antigen binding protein) that specifically interacts with a tumor-associated macrophage (e.g., by specifically binding to a cell surface receptor or molecule on the surface of a tumor associated macrophage). In some embodiments, the targeting unit does not specifically bind to non-tumor associated macrophage or cells. In some embodiments, the targeting unit specifically binds to CD206.

For preparation of monoclonal antibodies, any technique that provides for the production of antibody molecules by continuous cell lines in culture may be used (See e.g., Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y.). These include, but are not limited to, the hybridoma technique originally developed by Köhler and Milstein (Köhler and Milstein, Nature, 256:495-497 [1975]), as well as the trioma technique, the human B-cell hybridoma technique (See e.g., Kozbor et al., Immunol. Today, 4:72 [1983]), and the EBV-hybridoma technique to produce human monoclonal antibodies (Cole et al., in Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, Inc., pp. 77-96 [1985]). In other embodiments, suitable monoclonal antibodies, including recombinant chimeric monoclonal antibodies and chimeric monoclonal antibody fusion proteins are prepared as described herein.

According to the invention, techniques described for the production of single chain antibodies (U.S. Pat. No. 4,946,778; herein incorporated by reference) can be adapted to produce specific single chain antibodies as desired. An additional embodiment of the invention utilizes the techniques known in the art for the construction of Fab expression libraries (Huse et al., Science, 246:1275-1281 [1989]) to allow rapid and easy identification of monoclonal Fab fragments with the desired specificity.

In some embodiments, monoclonal antibodies are generated using the ABL-MYC method (See e.g., U.S. Pat. Nos. 5,705,150 and 5,244,656, each of which is herein incorporated by reference) (Neoclone, Madison, Wis.). ABL-MYC is a recombinant retrovirus that constitutively expresses v-abl and c-myc oncogenes. When used to infect antigen-activated splenocytes, this retroviral system rapidly induces antigen-specific plasmacytomas. ABL-MYC targets antigen-stimulated (Ag-stimulated) B-cells for transformation.

In some embodiments, biopanning as described in Pardon et al, Nat Protoc. 2014 Mar;9(3):674-93 is used to generate single domain antibodies. In some embodiments, to generate murine scFv units, phage-based biopanning strategies, of which there are several published protocols available, are used.

Antibody fragments that contain the idiotype (antigen binding region) of the antibody molecule can be generated by known techniques. For example, such fragments include but are not limited to: the F(ab′)2 fragment that can be produced by pepsin digestion of an antibody molecule; the Fab′ fragments that can be generated by reducing the disulfide bridges of an F(ab′)2 fragment, and the Fab fragments that can be generated by treating an antibody molecule with papain and a reducing agent.

Genes encoding antigen-binding proteins can be isolated by methods known in the art. In the production of antibodies, screening for the desired antibody can be accomplished by techniques known in the art (e.g., radioimmunoassay, ELISA (enzyme-linked immunosorbant assay), “sandwich” immunoassays, immunoradiometric assays, gel diffusion precipitin reactions, immunodiffusion assays, in situ immunoassays (using colloidal gold, enzyme or radioisotope labels, for example), Western Blots, precipitation reactions, agglutination assays (e.g., gel agglutination assays, hemagglutination assays, etc.), complement fixation assays, immunofluorescence assays, protein A assays, phage display biopanning, and immunoelectrophoresis assays, etc.) etc.

As used herein, the term “immunostimulatory agent” refers to any agent that stimulates an immune response. In some embodiments, the immune response is a cellular immune response (e.g., against a tumor associated macrophage). In some embodiments, the immunostimulatory agent is a cytokine (e.g., IL15 or a fragment thereof).

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to cancer immunotherapy. In particular, provided herein are fusion proteins for targeting tumor associated macrophages (TAMs, also known as tumor infiltrating macrophages) with immunostimulatory agents.

The ability of the immune system to fight cancer has been clearly demonstrated in recent years, highlighted by the massive clinical and commercial success of the immune checkpoint inhibitors. One of the key advantages offered by these drugs is that they have the potential to treat several cancer types and are supplied in an off-the-shelf manner. In contrast to personalized immunotherapies such as adoptive T-cell therapy or dendritic cell (DC) vaccines, they do not rely on customization for each patient. On the downside, only a minority of patients respond adequately, and checkpoint inhibitors have a challenging safety profile.

The present invention encompasses a new universal therapeutic concept that also targets a wide range of tumors and are supplied in an off-the-shelf manner, but which has a radically different mechanism of action. Whereas the checkpoint inhibitors require a pre-existing anti-tumor immune response in the patient, the present technology induces an in situ anti-tumor inflammatory focal immune response in the cancer tissue through targeted delivery of an immunostimulatory agent (e.g., as a non-limiting example, the highly pro-inflammatory cytokine IL15). Data presented herein shows complete eradication of large, established, tumors in mice within a few days without any signs of toxicity. See, e.g., example 2 and FIGS. 1-3.

Accordingly, provided herein are recombinant fusion proteins comprising of a targeting unit that binds to a protein displayed on or associated with TAMs linked to an immunostimulatory agent.

The fusion protein serves as a means of delivering an immunostimulatory agent directly to the tumor site with a high degree of specificity and selectivity, thereby locally activating the immune system to kill tumor cells. Since the targeted structure (e.g., as a non-limiting example, CD206) is not directly located on malignant cells, but on a cell type present in the majority of all tumors (e.g., the TAM), the compound is contemplated to be active against a wide variety of cancer types.

In contrast to conventional anti-cancer drugs, the fusion proteins of the present invention are not in themselves toxic, but work by stimulating immune cells to infiltrate, activate and divide within the tumor. The side effects of the treatment are therefore very mild compared to cytotoxic agents, which inevitably cause damage to healthy tissue. Moreover, the drug may have less off-target effects than checkpoint inhibitors, which may cause severe autoimmune pathology and tissue destruction due to their systemic activity.

Developing tumors are dependent on recruiting non-malignant cells that provide support to the cancer cells such as nutrients and factors required for growth and expansion. Macrophages constitute a notable class of such supportive cells, and are abundantly present within tumors in most types of human cancer. In contrast to cancer cells, which are unique to each patient, tumor-infiltrating cells such as macrophages are structurally identical between individuals. In contrast to tumor cell antigens, surface structures on tumor-infiltrating macrophages are not subject to mutations and immunoediting.

Destruction of tumor-supportive cells such as TAMs has been attempted as a strategy to inhibit tumor growth. Such approaches may impair tumor progression, and in some cases have been shown to induce remission, but this type of treatment is not curative. Rather than depleting TAMs, the present invention utilizes them as a target to deliver molecules that induce localized immune responses within tumors.

The present invention provides novel fusion proteins that target TAMs with an immunostimulatory molecule. Accordingly, in some embodiments, the present invention provides fusion proteins that comprise a targeting unit in operable association with an immunostimulatory agent. In preferred embodiments, the targeting unit is an antigen binding protein that binds to a protein molecule displayed on or otherwise associated with TAMs. Thus, the targeting unit preferably binds to the TAM to bring the immunostimulatory agent into close proximity with the TAM. The present invention is not limited to any particular theory of operation, but it will be appreciated that by targeting the TAMs with an immunostimulatory agent, the immune system is triggered to provide a local response at the site of the tumor, resulting in regression and/or destruction of the tumor by the immune system. The present invention is not limited to the use of any particular targeting unit. In some preferred embodiments, the targeting unit is an antigen binding protein. Preferred antigen binding protein include, but are not limited to, nanobodies, single domain antibodies (sdAb), single chain antibodies (scFv), immunoglobulins and fragments thereof that bind to an antigen (e.g., Fab fragments). Likewise, the present invention is not limited to any particular immunostimulatory agents. Suitable immunostimulatory agents include, but are not limited to, interleukins, interferons, and tumor necrosis factors. In some preferred embodiments, the targeting unit and the immunostimulatory agent are operably associated through a linker. Suitable linker include, but are not limited to, llama IgG2 linkers and (G₄S)₃ linkers. Each of these components will be described in more detail below.

1. Targeting Units

As mentioned above, the present invention is not limited to the use of any particular targeting unit. In some preferred embodiments, the targeting unit is an antigen binding protein. Preferred antigen binding protein include, but are not limited to an immunoglobulins, a Fab, F(ab′)₂, Fab′ single chain antibody, Fv, single chain (scFv), mono-specific antibody, bi-specific antibody, tri-specific antibody, multivalent antibody, chimeric antibody, humanized antibody, human antibody, CDR-grafted antibody, shark antibody, an immunoglobulin single variable domain (e.g., a nanobody or a single variable domain antibody), camelid antibody (e.g., from the Camelidae family) microbody, intrabody (e.g., intracellular antibody), and/or de-fucosylated antibody and/or derivative thereof. Mimetics of binding agents and/or antibodies are also provided.

In some preferred embodiments, the targeting units are antigen binding proteins that specifically bind to CD206, FOLR2, LGMN, CD204, CD163, or CD301. When the targeting unit is an antigen binding protein, the antigen binding protein may be made identified and cloned as is known in the art and as described in more detail below. Recombinant DNA techniques may then be used to produce a construct encoding a fusion protein including the antigen binding protein in operable association with an immunostimulatory agent.

In some embodiments, the targeting unit is an immunoglobulin single variable domain. As used herein, an “immunoglobulin single variable domain” is an antigen-binding domain or fragment that comprises an amino acid sequence that comprises four framework regions (FR) and three complementarity determining regions (CDR) according to the following formula (1):

FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4  (1);

or any suitable fragment thereof (which will then usually contain at least some of the amino acid residues that form at least one of the complementarity determining regions), and in which FR1 to FR4 refer to framework regions 1 to 4, respectively, and in which CDR1 to CDR3 refer to the complementarity determining regions 1 to 3, respectively.

Immunoglobulin single variable domains comprising 4 FRs and 3 CDRs are known to the person skilled in the art and have been described. See, e.g., Wesolowski J., V. Alzogaray, J. Reyelt, M. Unger, K. Juarez, M. Urrutia, A. Cauerhiff, W. Danquah, B. Rissiek, F. Scheuplin, N. Schwarz, S. Adriouch, O. Boyer, M. Seman, A. Licea, D. V. Serreze, F. A. Goldbaum, F. Haag, and F. Koch-Nolte. (2009). Single domain antibodies: promising experimental and therapeutic tools in infection and immunity Med. Microbiol. Immunol. 198, 157-174. Typical, but non-limiting, examples of immunoglobulin single variable domains include light chain variable domain sequences (e.g., a V_(L), domain sequence), or heavy chain variable domain sequences (e.g., a V_(H) domain sequence), which are usually derived from conventional four-chain antibodies. Preferably, the immunoglobulin single variable domains are derived from camelid antibodies, preferably from heavy chain camelid antibodies, devoid of light chains, and are known as V_(H)H domain sequences or nanobodies (as described further herein).

In some embodiments, the targeting unit is a nanobody. A nanobody (Nb) is the smallest functional fragment or single variable domain (V_(H)H) of a naturally occurring single-chain antibody and is known to the person skilled in the art. They are derived from heavy chain only antibodies, seen in camelids. See, e.g., Hamers-Casterman C., Atarhouch T., Muyldermans S., Robinson G., Hamers C., Songa E., Bendahman N & Hamers R., 1993, Nature 363, p. 446-448; Desmyter A., T. Transue., M. Ghahroudi, M. Dao-Thi, F. Poortmans, R. Hamers, S. Muyldermans and L. Wyns, 1996, Nat. Struct. Biol., p. 803-811. In the family of “camelids” immunoglobulins devoid of light polypeptide chains are found. “Camelids” comprise old world camelids (Camelus bactrianus and Camelus dromedarius) and new world camelids (for example, Lama paccos, Lama glama, Lama guanicoe and Lama vicugna). The single variable domain heavy chain antibody is herein designated as a Nanobody or a V_(H)H antibody. Nanobody™, Nanobodies™ and Nanoclone™ are trademarks of Ablynx NV (Belgium). The small size and unique biophysical properties of Nbs excel conventional antibody fragments for the recognition of uncommon or hidden epitopes and for binding into cavities or active sites of protein targets. Further, Nbs can be designed as multi-specific and multivalent antibodies (as defined further herein) or attached to reporter molecules. Conrath K., M. Lauwereys, M. Galleni, A. Matagne, J-M. Frere, J. Kinne, L. Wyns, and S. Muyldermans (2001). beta-Lactamase Inhibitors Derived from Single-Domain Antibody Fragments Elicited in the Camelidae Antimicrob Agents. Chemother 45, 2807-2812. Nbs are stable, survive the gastro-intestinal system and can easily be manufactured. Therefore, Nbs can be used in many applications including drug discovery and therapy, but also as a versatile and valuable tool for purification, functional study and crystallization of proteins. See, e.g., Saerens D., G. Ghassabeh, S. Muyldermans, 2008, Current Opinion in Pharmacology 8, p. 600-608.

The nanobodies of the invention generally comprise a single amino acid chain that can be considered to comprise four “framework regions” or FRs and three “complementarity determining regions” or CDRs, according to formula (1) (as defined above). The term “complementarity determining region” or “CDR” refers to variable regions in nanobodies and contains the amino acid sequences capable of specifically binding to antigenic targets. These CDR regions account for the basic specificity of the nanobody for a particular antigenic determinant structure. Such regions are also referred to as “hypervariable regions.” The nanobodies have three CDR regions, each non-contiguous with the others (termed CDR1, CDR2, CDR3). The delineation of the FR and CDR sequences is often based on the IMGT unique numbering system for V-domains and V-like domains. (See, e.g., Lefranc M. P., C. Pommie, et al. (2003). “IMGT unique numbering for immunoglobulin and T cell receptor variable domains and Ig superfamily V-like domains.” Developmental and Comparative Immunology 27(1): 55-77.) Alternatively, the delineation of the FR and CDR sequences can be done by using the Kabat numbering system as applied to V_(H)H domains from Camelids in the article of Riechmann and Muyldermans. (See, e.g., Riechmann and Muyldermans J. Immunol. Methods 2000; 240: 185-195.) As will be known by the person skilled in the art, the nanobodies can in particular be characterized by the presence of one or more Camelidae hallmark residues in one or more of the framework sequences (according to Kabat numbering), as described, for example, in WO 08/020,079, on page 75, Table A-3, incorporated herein by reference).

Non-limiting examples of nanobodies according to the present invention are as described herein and include anti-human, anti-mouse and cross-reactive anti-human/anti-mouse nanobodies. In some embodiments, the antibodies specifically bind to one of the following proteins on or in a Tumor Associated Macrophage (TAM): CD206 (macrophage mannose receptor (MMR); see, e.g., US Pat. Publ. 20120301394, incorporated herein by reference in its entirety), folate receptor beta (FOLR2), legumain (LGMN), CD204, CD163, or CD301. In a specific embodiment, the nanobodies of the present invention may comprise at least one of the complementarity determining regions (CDRs) derived from any of the nanobodies described herein. Preferably, the nanobodies of the present invention comprise a CDR1, a CDR2 and a CDR3 from one of the nanobodies described herein. More specifically, the nanobodies, or a functional fragment thereof, can be selected from the group comprising SEQ ID NOs: 30-56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, and 112 which bind to CD206 and SEQ ID NO: 122, which binds to FOLR2. The nanobodies identified by 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, and 112 are codon and expression optimized. A “functional fragment” or a “suitable fragment,” as used herein, may, for example, comprise one of the CDR loops. Preferably, the functional fragment comprises CDR3. More specifically, the nanobodies consist of any of SEQ ID NOs: 30-56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, and 112 which bind to CD206 and SEQ ID NO: 122, which binds to FOLR2. In still another embodiment, a nucleic acid sequence encoding any of the above nanobodies or functional fragments is also part of the present invention (for example, SEQ ID NOs:3, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107 and 111, which encode nanobodies which bind to CD206 and SEQ ID NO:123 which encodes a single domain antibody (sdAM) or nanobody which binds to FOLR2). The nanobodies encoded by 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107 and 111 are expression and codon optimized. Further, the present invention also envisages expression vectors comprising nucleic acid sequences encoding any of the above nanobodies or functional fragments thereof, as well as host cells expressing such expression vectors. Suitable expression systems include constitutive and inducible expression systems in bacteria or yeasts, virus expression systems, such as baculovirus, semliki forest virus and lentiviruses, or transient transfection in insect or mammalian cells. Suitable host cells include E. coli, Lactococcus lactis, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Pichia pastoris, and the like. Suitable animal host cells include HEK 293, COS, S2, CHO, NS0, DT40 and the like. The cloning, expression and/or purification of the nanobodies can be done according to techniques known by the skilled person in the art. For the sake of clarity, it is expected that at least some of the nanobodies identified herein may also be cross-reactive with macrophage mannose receptors of other mammalian species.

It will be understood that nanobodies may be identified with reference to the nucleotide and/or amino acid sequence corresponding to the variable and/or complementarity determining regions (“CDRs”) thereof. For instance, an exemplary nanobody that is derived from, or is related to the nanobodies described above may comprise a variable domain. The variable domains typically comprise one or more CDRs that in large part determine the binding specificity of the nanobody. Nanobodies of the present invention may be identified by analysis of the nucleotide sequences encoding the CDRs or variable regions. The nanobodies of the present invention may also be identified by analysis of the amino acid sequences of (e.g., which may be encoded by the nucleotide sequences) of the CDRs or variable regions. Table 1 provides an identification of the CDRs of various nanobodies of the present invention which are listed in column 1 of the table. In some embodiments, the present invention provides nanobodies wherein one, two or all three of the CDRs of the nanobody have at least 60%, 70%, 80%, 90% or 100% identity to the CDRs identified for each nanobody. In other words, the present invention contemplates that variants of the listed CDRs are within the scope of the invention and that the CDRs may be altered by, for example, substitution, deletion, or addition mutations. It will also be recognized that the CDRs from the nanobodies that bind CD206 may be substituted for one another in a given nanobody variable domain. For example, a CDR1 from one of the nanobodies may be substituted with a CDR1 from another nanobody in Table 1, a CDR2 from one of the nanobodies may be substituted with a CDR2 from another nanobody in Table 1, and a CDR3 from one of the nanobodies may be substituted with a CDR3 from another nanobody in Table 1.

TABLE 1 Nanobody Protein Sequence bound by identifier CDR1 CDR2 CDR3 Nanobody SEQ ID GSIFTIN ITSGGSTN VVVTTTPYSDY CD206 NO: 30 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 171 SEQ ID ARIFSSY VNGGSSST AGRAGPLAASYRYDY CD206 NO: 31 SEQ ID SEQ ID NO: 175 SEQ ID NO: 176 NO: 174 SEQ ID ARIFSSY VNGGSSST VVVTTTPYSDY CD206 NO: 32 SEQ ID SEQ ID NO: 175 SEQ ID NO: 173 NO: 174 SEQ ID GSIFTIN ITSGGSTN AGRAGPLAASYRYDY CD206 NO: 33 SEQ ID SEQ ID NO: 172 SEQ ID NO: 176 NO: 171 SEQ ID GSIFTIN ITRGGSTN VVVTTTPYSDY CD206 NO: 34 SEQ ID SEQ ID NO: 177 SEQ ID NO: 173 NO: 171 SEQ ID GSIFTIN ITSGGSTN VVVTTTAYSDY CD206 NO: 35 SEQ ID SEQ ID NO: 172 SEQ ID NO: 178 NO: 171 SEQ ID GSIFTIN ITSGGSTN VVVTTTPYSDY CD206 NO: 36 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 171 SEQ ID GSIFTIN LTSGGSTN VVVTTTPYADY CD206 NO: 37 SEQ ID SEQ ID NO: 179 SEQ ID NO: 180 NO: 171 SEQ ID GSIFTIN ITSGGSTN VVVTTPYSDY CD206 NO: 38 SEQ ID SEQ ID NO: 172 SEQ ID NO: 181 NO: 171 SEQ ID GSIFTIN ITSGGSTN VVVTTTPYSDY CD206 NO: 39 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 171 SEQ ID GSIFTIN VNGGSSST VVVTTTPYSDY CD206 NO: 40 SEQ ID SEQ ID NO: 175 SEQ ID NO: 173 NO: 171 SEQ ID GSICTSN ITSGGSTN VVVTTTPYSDY CD206 NO: 41 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 182 SEQ ID GLTFSIR IMWSGGAT VVVTTTPYSDY CD206 NO: 42 SEQ ID SEQ ID NO: 184 SEQ ID NO: 173 NO: 183 SEQ ID WKHLHY ITSGGSTN VVVTTTPYSDY CD206 NO: 43 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 185 SEQ ID GSIFTIN ITSGGSTN VVVTTTPYSDY CD206 NO: 44 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 171 SEQ ID VSIFTIN NTSGGSTN VVVTTTQYSDY CD206 NO: 45 SEQ ID SEQ ID NO: 187 SEQ ID NO: 194 NO: 186 SEQ ID GSIFTIN ITSGGSTN VVVTTTPYSDY CD206 NO: 46 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 171 SEQ ID ARIFSSY ITSGGSTN VVVTTTPYSDY CD206 NO: 47 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 174 SEQ ID GSLFTIN ITSGGSTN LVVPPTPYSVY CD206 NO: 48 SEQ ID SEQ ID NO: 172 SEQ ID NO: 189 NO: 188 SEQ ID GSIFTIN ITSGGSTN VVVTTTPYSDY CD206 NO: 49 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 171 SEQ ID GSIFTIN ITSGGSTN VVVTTTPYSDY CD206 NO: 50 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 171 SEQ ID GSIFTIN STSGGSPN GGGSSTPDSDY CD206 NO: 51 SEQ ID SEQ ID NO: 190 SEQ ID NO: 191 NO: 171 SEQ ID GSIFTSN ITSGGSTN VVVTTTPYSDY CD206 NO: 52 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 192 SEQ ID GSIFTIN ITSGGSTN VVVTTTPYSDY CD206 NO: 53 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 171 SEQ ID GSIFTIN ITSGGSTN VVVTTTPEADY CD206 NO: 54 SEQ ID SEQ ID NO: 172 SEQ ID NO: 193 NO: 171 SEQ ID GSIFTIN ITSGGSTN VVVTTTPYSDY CD206 NO: 55 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 171 SEQ ID GSIFTIN ITSGGSTN VVVTTTPYSDY CD206 NO: 56 SEQ ID SEQ ID NO: 172 SEQ ID NO: 173 NO: 171 SEQ ID GRTFSNY ISQSGSITY GNSFKSNDHWASTY FOLR2 NO: 122 SEQ ID SEQ ID NO: 196 SEQ ID NO: 197 NO: 195

It should be noted that the term nanobody as used herein in its broadest sense is not limited to a specific biological source or to a specific method of preparation. For example, the nanobodies of the invention can generally be obtained: (1) by isolating the V_(H)H domain of a naturally occurring heavy chain antibody; (2) by expression of a nucleotide sequence encoding a naturally occurring V_(H)H domain; (3) by “humanization” of a naturally occurring V_(H)H domain or by expression of a nucleic acid encoding a such humanized V_(H)H domain; (4) by “camelization” of a naturally occurring VH domain from any animal species, and in particular from a mammalian species, such as from a human being, or by expression of a nucleic acid encoding such a camelized VH domain; (5) by “camelization” of a “domain antibody” or “Dab” as described in the art, or by expression of a nucleic acid encoding such a camelized VH domain; (6) by using synthetic or semi-synthetic techniques for preparing proteins, polypeptides or other amino acid sequences known per se; (7) by preparing a nucleic acid encoding a nanobody using techniques for nucleic acid synthesis known per se, followed by expression of the nucleic acid thus obtained; and/or (8) by any combination of one or more of the foregoing.

One preferred class of nanobodies corresponds to the V_(H)H domains of naturally occurring heavy chain antibodies directed against a macrophage mannose receptor, also known as CD206. As further described herein, such V_(H)H sequences can generally be generated or obtained by suitably immunizing a species of Camelid with a MMR (i.e., so as to raise an immune response and/or heavy chain antibodies directed against a MMR), by obtaining a suitable biological sample from the Camelid (such as a blood sample, or any sample of B-cells), and by generating V_(H)H sequences directed against a MMR, starting from the sample, using any suitable technique known per se. Such techniques will be clear to the skilled person. Alternatively, such naturally occurring V_(H)H domains against MMR can be obtained from naive libraries of Camelid V_(H)H sequences, for example, by screening such a library using MMR or at least one part, fragment, antigenic determinant or epitope thereof using one or more screening techniques known per se. Such libraries and techniques are, for example, described in WO9937681, WO0190190, WO03025020 and WO03035694. Alternatively, improved synthetic or semi-synthetic libraries derived from naive V_(H)H libraries may be used, such as V_(H)H libraries obtained from naive V_(H)H libraries by techniques such as random mutagenesis and/or CDR shuffling, as, for example, described in WO0043507. Yet another technique for obtaining V_(H)H sequences directed against a MMR involves suitably immunizing a transgenic mammal that is capable of expressing heavy chain antibodies (i.e., so as to raise an immune response and/or heavy chain antibodies directed against a MMR), obtaining a suitable biological sample from the transgenic mammal (such as a blood sample, or any sample of B-cells), and then generating V_(H)H sequences directed against a MMR starting from the sample, using any suitable technique known per se. For example, for this purpose, the heavy chain antibody-expressing mice and the further methods and techniques described in WO02085945 and in WO04049794 can be used.

Accordingly, the invention encompasses methods of generating immunoglobulin single variable domains according to the invention. As a non-limiting example, a method is provided of generating nanobodies directed against or specifically binding to a protein displayed on or associated with a TAM (e.g., CD206, FOLR2, LGMN, CD204, CD163, or CD301, referred to collectively as TAM targeting protein) by immunization of an animal with the desired TAM targeting protein. For the immunization of an animal with the TAM targeting protein, the TAM targeting protein may be produced and purified using conventional methods that may employ expressing a recombinant form of the TAM targeting protein in a host cell, and purifying the TAM targeting protein using affinity chromatography and/or antibody-based methods. Any suitable animal, e.g., a warm-blooded animal, in particular a mammal such as a rabbit, mouse, rat, camel, sheep, cow, shark, or pig or a bird such as a chicken or turkey, may be immunized using any of the techniques well known in the art suitable for generating an immune response. The screening for nanobodies, as a non-limiting example, specifically binding to a TAM targeting protein may, for example, be performed by screening a set, collection or library of cells that express heavy chain antibodies on their surface (e.g., B-cells obtained from a suitably immunized Camelid), or bacteriophages that display a fusion of genIII and nanobody at their surface, by screening of a (naive or immune) library of V_(H)H sequences or nanobody sequences, or by screening of a (naive or immune) library of nucleic acid sequences that encode V_(H)H sequences or nanobody sequences, which may all be performed in a manner known per se, and which method may optionally further comprise one or more other suitable steps, such as, for example, and without limitation, a step of affinity maturation, a step of expressing the desired amino acid sequence, a step of screening for binding and/or for activity against the desired antigen (in this case, the TAM targeting protein), a step of determining the desired amino acid sequence or nucleotide sequence, a step of introducing one or more humanizing substitutions, a step of formatting in a suitable multivalent and/or multispecific format, a step of screening for the desired biological and/or physiological properties (i.e., using a suitable assay known in the art), and/or any combination of one or more of such steps, in any suitable order.

A particularly preferred class of immunoglobulin single variable domains of the invention comprises nanobodies with an amino acid sequence that corresponds to the amino acid sequence of a naturally occurring V_(H)H domain, but that has been “humanized,” i.e., by replacing one or more amino acid residues in the amino acid sequence of the naturally occurring V_(H)H sequence (and in particular in the framework sequences) by one or more of the amino acid residues that occur at the corresponding position(s) in a V_(H) domain from a conventional four-chain antibody from a human being. This can be performed in a manner known per se, which will be clear to the skilled person, on the basis of the further description herein and the prior art on humanization. Again, it should be noted that such humanized nanobodies of the invention can be obtained in any suitable manner known per se (i.e., as indicated under points (1)-(8) above) and thus are not strictly limited to polypeptides that have been obtained using a polypeptide that comprises a naturally occurring V_(H)H domain as a starting material. Humanized nanobodies may have several advantages, such as a reduced immunogenicity, compared to the corresponding naturally occurring V_(H)H domains. Such humanization generally involves replacing one or more amino acid residues in the sequence of a naturally occurring V_(H)H with the amino acid residues that occur at the same position in a human V_(H) domain, such as a human VH3 domain. The humanizing substitutions should be chosen such that the resulting humanized nanobodies still retain the favorable properties of nanobodies as defined herein. The skilled person will be able to select humanizing substitutions or suitable combinations of humanizing substitutions which optimize or achieve a desired or suitable balance between the favorable properties provided by the humanizing substitutions on the one hand and the favorable properties of naturally occurring V_(H)H domains on the other hand.

For example, both “humanization” and “camelization” can be performed by providing a nucleotide sequence that encodes a naturally occurring V_(H)H domain or VH domain, respectively, and then changing, in a manner known per se, one or more codons in the nucleotide sequence in such a way that the new nucleotide sequence encodes a “humanized” or “camelized” nanobody of the invention, respectively. This nucleic acid can then be expressed in a manner known per se, so as to provide the desired nanobody of the invention. Alternatively, based on the amino acid sequence of a naturally occurring V_(H)H domain or VH domain, respectively, the amino acid sequence of the desired humanized or camelized Nanobody of the invention, respectively, can be designed and then synthesized de novo using techniques for peptide synthesis known per se. Also, based on the amino acid sequence or nucleotide sequence of a naturally occurring V_(H)H domain or VH domain, respectively, a nucleotide sequence encoding the desired humanized or camelized Nanobody of the invention, respectively, can be designed and then synthesized de novo using techniques for nucleic acid synthesis known per se, after which the nucleic acid thus obtained can be expressed in a manner known per se, so as to provide the desired nanobody of the invention. Other suitable methods and techniques for obtaining the nanobodies of the invention and/or nucleic acids encoding the same, starting from naturally occurring VH sequences or preferably VHH sequences, will be clear from the skilled person, and may, for example, comprise combining one or more parts of one or more naturally occurring VH sequences (such as one or more FR sequences and/or CDR sequences), one or more parts of one or more naturally occurring V.sub.HH sequences (such as one or more FR sequences or CDR sequences), and/or one or more synthetic or semi-synthetic sequences, in a suitable manner, so as to provide a nanobody of the invention or a nucleotide sequence or nucleic acid encoding the same.

Also within the scope of the invention are natural or synthetic analogs, mutants, variants, alleles, homologs and orthologs (herein collectively referred to as “variants”) of the immunoglobulin single variable domains of the invention as defined herein. Thus, according to one embodiment of the invention, the term “immunoglobulin single variable domain of the invention” in its broadest sense also covers such variants, in particular variants of the nanobodies of SEQ ID NOs: 30-56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, and 112 which bind to CD206 and SEQ ID NO: 122, which binds to FOLR2. Generally, in such variants, one or more amino acid residues may have been replaced, deleted and/or added, compared to the nanobodies of the invention as defined herein. Such substitutions, insertions or deletions may be made in one or more of the framework regions and/or in one or more of the CDRs. Variants, as used herein, are sequences wherein each or any framework region and each or any complementarity determining region shows at least 80% identity, preferably at least 85% identity, more preferably 90% identity, even more preferably 95% identity or, still even more preferably 99% identity with the corresponding region in the reference sequence (i.e., FR1 variant versus FR1 reference, CDR1 variant versus CDR1 reference, FR2 variant versus FR2 reference, CDR2 variant versus CDR2 reference, FR3 variant versus FR3 reference, CDR3 variant versus CDR3 reference, FR4 variant versus FR4 reference), as can be measured electronically by making use of algorithms such as PILEUP and BLAST. (See, e.g., Higgins & Sharp, CABIOS 5:151 (1989); Altschul S. F., W. Gish, W. Miller, E. W. Myers, D. J. Lipman. Basic local alignment search tool. J. Mol. Biol. 1990; 215:403-10.) Software for performing BLAST analyses is publicly available through the National Center for Biotechnology Information (on the worldwide web at ncbi.nlm.nih.gov/). Such variants of immunoglobulin single variable domains may be of particular advantage since they may have improved potency or other desired properties.

A “deletion” is defined here as a change in either amino acid or nucleotide sequence in which one or more amino acid or nucleotide residues, respectively, are absent as compared to an amino acid sequence or nucleotide sequence of a parental polypeptide or nucleic acid. Within the context of a protein, a deletion can involve deletion of about two, about five, about ten, up to about twenty, up to about thirty or up to about fifty or more amino acids. A protein or a fragment thereof may contain more than one deletion.

An “insertion” or “addition” is that change in an amino acid or nucleotide sequences which has resulted in the addition of one or more amino acid or nucleotide residues, respectively, as compared to an amino acid sequence or nucleotide sequence of a parental protein. “Insertion” generally refers to addition to one or more amino acid residues within an amino acid sequence of a polypeptide, while “addition” can be an insertion or refer to amino acid residues added at an N- or C-terminus, or both termini. Within the context of a protein or a fragment thereof, an insertion or addition is usually of about one, about three, about five, about ten, up to about twenty, up to about thirty or up to about fifty or more amino acids. A protein or fragment thereof may contain more than one insertion.

A “substitution,” as used herein, results from the replacement of one or more amino acids or nucleotides by different amino acids or nucleotides, respectively as compared to an amino acid sequence or nucleotide sequence of a parental protein or a fragment thereof. It is understood that a protein or a fragment thereof may have conservative amino acid substitutions which have substantially no effect on the protein's activity. By conservative substitutions is intended combinations such as gly, ala; val, ile, leu, met; asp, glu; asn, gln; ser, thr; lys, arg; cys, met; and phe, tyr, trp.

By means of non-limiting examples, a substitution may, for example, be a conservative substitution (as described herein) and/or an amino acid residue may be replaced by another amino acid residue that naturally occurs at the same position in another V_(H)H domain. Thus, any one or more substitutions, deletions or insertions, or any combination thereof, that either improve the properties of the nanobody of the invention or that at least do not detract too much from the desired properties or from the balance or combination of desired properties of the nanobody of the invention (i.e., to the extent that the nanobody is no longer suited for its intended use) are included within the scope of the invention. A skilled person will generally be able to determine and select suitable substitutions, deletions or insertions, or suitable combinations of thereof, based on the disclosure herein and optionally after a limited degree of routine experimentation, which may, for example, involve introducing a limited number of possible substitutions and determining their influence on the properties of the nanobodies thus obtained.

According to particularly preferred embodiments, variants of the immunoglobulin single variable domains, in particular the nanobodies of the present invention may have a substitution, deletion or insertion, of one, two or three amino acids in one, two or three of the CDRs, more specifically (i) in CDR1 or CDR2 or CDR3; (ii) in CDR1 and CDR2, or, in CDR1 and CDR3, or, in CDR2 and CDR3; (iii) in CDR1 and CDR2 and CDR3. More preferably, variants of the immunoglobulin single variable domains, in particular the nanobodies, of the present invention may have a conservative substitution (as defined herein) of one, two or three amino acids in one, two or three of the CDRs, more specifically (i) in CDR1 or CDR2 or CDR3; (ii) in CDR1 and CDR2, or, in CDR1 and CDR3, or, in CDR2 and CDR3; (iii) in CDR1 and CDR2 and CDR3.

Further, depending on the host organism used to express the immunoglobulin single variable domain of the invention, such deletions and/or substitutions may be designed in such a way that one or more sites for post-translational modification (such as one or more glycosylation sites) are removed, as will be within the ability of the person skilled in the art. Alternatively, substitutions or insertions may be designed so as to introduce one or more sites for attachment of functional groups (as described herein), for example, to allow site-specific pegylation.

Examples of modifications, as well as examples of amino acid residues within the immunoglobulin single variable domain, preferably the nanobody sequence, that can be modified (i.e., either on the protein backbone but preferably on a side chain), methods and techniques that can be used to introduce such modifications and the potential uses and advantages of such modifications will be clear to the skilled person. For example, such a modification may involve the introduction (e.g., by covalent linking or in another suitable manner) of one or more functional groups, residues or moieties into or onto the immunoglobulin single variable domain of the invention, and in particular of one or more functional groups, residues or moieties that confer one or more desired properties or functionalities to the immunoglobulin single variable domain of the invention. Examples of such functional groups and of techniques for introducing them will be clear to the skilled person, and can generally comprise all functional groups and techniques mentioned in the general background art cited hereinabove as well as the functional groups and techniques known per se for the modification of pharmaceutical proteins, and in particular for the modification of antibodies or antibody fragments (including ScFvs and single domain antibodies), for which reference is, for example, made to Remington's Pharmaceutical Sciences, 16th ed., Mack Publishing Co., Easton, Pa. (1980). Such functional groups may, for example, be linked directly (for example, covalently) to a immunoglobulin single variable domain of the invention, or optionally via a suitable linker or spacer, as will again be clear to the skilled person. One of the most widely used techniques for increasing the half-life and/or reducing immunogenicity of pharmaceutical proteins comprises attachment of a suitable pharmacologically acceptable polymer, such as poly(ethyleneglycol) (PEG) or derivatives thereof (such as methoxypoly(ethyleneglycol) or mPEG). Generally, any suitable form of pegylation can be used, such as the pegylation used in the art for antibodies and antibody fragments (including but not limited to (single) domain antibodies and ScFvs); reference is made to, for example, Chapman, Nat. Biotechnol., 54, 531-545 (2002); by Veronese and Harris, Adv. Drug Deliv. Rev. 54, 453-456 (2003), by Harris and Chess, Nat. Rev. Drug. Discov., 2, (2003) and in WO04060965. Various reagents for pegylation of proteins are also commercially available, for example, from Nektar Therapeutics, USA. Preferably, site-directed pegylation is used, in particular via a cysteine-residue (see, for example, Yang et al., Protein Engineering, 16, 10, 761-770 (2003). For example, for this purpose, PEG may be attached to a cysteine residue that naturally occurs in a nanobody of the invention, a nanobody of the invention may be modified so as to suitably introduce one or more cysteine residues for attachment of PEG, or an amino acid sequence comprising one or more cysteine residues for attachment of PEG may be fused to the N- and/or C-terminus of a nanobody of the invention, all using techniques of protein engineering known per se to the skilled person. Preferably, for the immunoglobulin single variable domains and proteins of the invention, a PEG is used with a molecular weight of more than 5000, such as more than 10,000 and less than 200,000, such as less than 100,000; for example, in the range of 20,000-80,000. Another, usually less preferred modification comprises N-linked or O-linked glycosylation, usually as part of co-translational and/or post-translational modification, depending on the host cell used for expressing the immunoglobulin single variable domain or polypeptide of the invention. Another technique for increasing the half-life of an immunoglobulin single variable domain may comprise the engineering into bifunctional constructs (for example, one nanobody against the target MMR and one against a serum protein such as albumin) or into fusions of immunoglobulin single variable domains with peptides (for example, a peptide against a serum protein such as albumin).

Yet another modification may comprise the introduction of one or more detectable labels or other signal-generating groups or moieties, depending on the intended use of the labeled nanobody. Suitable labels and techniques for attaching, using and detecting them will be clear to the skilled person and, for example, include, but are not limited to, fluorescent labels (such as fluorescein, isothiocyanate, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, o-phthaldehyde, and fluorescamine and fluorescent metals such as Eu or others metals from the lanthanide series), phosphorescent labels, chemiluminescent labels or bioluminescent labels (such as luminal, isoluminol, theromatic acridinium ester, imidazole, acridinium salts, oxalate ester, dioxetane or GFP and its analogs), radio-isotopes, metals, metals chelates or metallic cations or other metals or metallic cations that are particularly suited for use in in vivo, in vitro or in situ diagnosis and imaging, as well as chromophores and enzymes (such as malate dehydrogenase, staphylococcal nuclease, delta-V-steroid isomerase, yeast alcohol dehydrogenase, alpha-glycerophosphate dehydrogenase, triose phosphate isomerase, biotinavidin peroxidase, horseradish peroxidase, alkaline phosphatase, asparaginase, glucose oxidase, beta-galactosidase, ribonuclease, urease, catalase, glucose-VI-phosphate dehydrogenase, glucoamylase and acetylcholine esterase). Other suitable labels will be clear to the skilled person and, for example, include moieties that can be detected using NMR or ESR spectroscopy. Such labeled nanobodies and polypeptides of the invention may, for example, be used for in vitro, in vivo or in situ assays (including immunoassays known per se such as ELISA, RIA, EIA and other “sandwich assays,” etc.) as well as in vivo diagnostic and imaging purposes, depending on the choice of the specific label. As will be clear to the skilled person, another modification may involve the introduction of a chelating group, for example, to chelate one of the metals or metallic cations referred to above. Suitable chelating groups, for example, include, without limitation, diethyl-enetriaminepentaacetic acid (DTPA) or ethylenediaminetetraacetic acid (EDTA). Yet another modification may comprise the introduction of a functional group that is one part of a specific binding pair, such as the biotin-(strept)avidin binding pair. Such a functional group may be used to link the nanobody of the invention to another protein, polypeptide or chemical compound that is bound to the other half of the binding pair, i.e., through formation of the binding pair. For example, a nanobody of the invention may be conjugated to biotin, and linked to another protein, polypeptide, compound or carrier conjugated to avidin or streptavidin. For example, such a conjugated nanobody may be used as a reporter, for example, in a diagnostic system where a detectable signal-producing agent is conjugated to avidin or streptavidin. Such binding pairs may, for example, also be used to bind the nanobody of the invention to a carrier, including carriers suitable for pharmaceutical purposes. One non-limiting example are the liposomal formulations described by Cao and Suresh, Journal of Drug Targeting, 8, 4, 257 (2000). Such binding pairs may also be used to link a therapeutically active agent to the nanobody of the invention.

According to a preferred embodiment, the immunoglobulin single variable domain of the present invention is fused to a detectable label, either directly or through a linker. Preferably, the detectable label is a radio-isotope or radioactive tracer, which is suitable for medical applications, such as in in vivo nuclear imaging. Examples include, without the purpose of being limitative, ⁹⁹mTc, ¹²³I, ¹²⁵I, ¹¹¹In, ¹⁸F, ⁶⁴Cu, ⁶⁷Ga, ⁶⁸Ga, and any other radio-isotope which can be used in animals, in particular mouse or human.

In still another embodiment, the immunoglobulin single variable domain of the present invention is fused to a moiety selected from the group consisting of a toxin, or to a cytotoxic drug, or to an enzyme capable of converting a prodrug into a cytotoxic drug, or to a radionuclide, or coupled to a cytotoxic cell, either directly or through a linker.

As used herein, “linkers” are peptides of 1 to 50 amino acids length and are typically chosen or designed to be unstructured and flexible. These include, but are not limited to, synthetic peptides rich in Gly, Ser, Thr, Gln, Glu or further amino acids that are frequently associated with unstructured regions in natural proteins. (See, e.g., Dosztanyi Z., V. Csizmok, P. Tompa, and I. Simon (2005). IUPred: web server for the prediction of intrinsically unstructured regions of proteins based on estimated energy content. Bioinformatics (Oxford, England), 21(16), 3433-4.) Non-limiting examples of suitable linker sequences are described in the Example section, and include (G₄S)₃ (GGGGSGGGGSGGGGS; SEQ ID NO:110), llama IgG2 hinge (AHHSEDPSSKAPKAPMA; SEQ ID NO:109, see also, SEQ ID NO:113) or human IgA hinge (SPSTPPTPSPSTPPAS SEQ ID NO:147) linkers.

In other embodiments, the targeting unit is an immunoglobulin or fragment thereof. Examples include, but are not limited to, aptamers and immunoglobulins. Immunoglobulins (antibodies) are proteins generated by the immune system to provide a specific molecule capable of complexing with an invading molecule commonly referred to as an antigen. Natural antibodies have two identical antigen-binding sites, both of which are specific to a particular antigen. The antibody molecule recognizes the antigen by complexing its antigen-binding sites with areas of the antigen termed epitopes. The epitopes fit into the conformational architecture of the antigen-binding sites of the antibody, enabling the antibody to bind to the antigen.

The immunoglobulin molecule is composed of two identical heavy and two identical light polypeptide chains, held together by interchain disulfide bonds. Each individual light and heavy chain folds into regions of about 110 amino acids, assuming a conserved three-dimensional conformation. The light chain comprises one variable region (termed V_(L)) and one constant region (CO, while the heavy chain comprises one variable region (V_(H)) and three constant regions (C_(H)1, C_(H)2 and C_(H)3). Pairs of regions associate to form discrete structures. In particular, the light and heavy chain variable regions, V_(L) and V_(H), associate to form an “Fv” area that contains the antigen-binding site.

The variable regions of both heavy and light chains show considerable variability in structure and amino acid composition from one antibody molecule to another, whereas the constant regions show little variability. Each antibody recognizes and binds an antigen through the binding site defined by the association of the heavy and light chain, variable regions into an Fv area. The light-chain variable region V_(L) and the heavy-chain variable region V_(H) of a particular antibody molecule have specific amino acid sequences that allow the antigen-binding site to assume a conformation that binds to the antigen epitope recognized by that particular antibody.

Within the variable regions are found regions in which the amino acid sequence is extremely variable from one antibody to another. Three of these so-called “hypervariable” regions or “complementarity-determining regions” (CDR's) are found in each of the light and heavy chains. The three CDRs from a light chain and the three CDRs from a corresponding heavy chain form the antigen-binding site.

Cleavage of naturally occurring antibody molecules with the proteolytic enzyme papain generates fragments that retain their antigen-binding site. These fragments, commonly known as Fab's (for Fragment, antigen binding site) are composed of the C_(L), V_(L), C_(H)1 and V_(H) regions of the antibody. In the Fab the light chain and the fragment of the heavy chain are covalently linked by a disulfide linkage.

Monoclonal antibodies against target antigens (e.g., a cell surface protein, such as receptors) are produced by a variety of techniques including conventional monoclonal antibody methodologies such as the somatic cell hybridization techniques of Kohler and Milstein, Nature, 256:495 (1975). Although in some embodiments, somatic cell hybridization procedures are preferred, other techniques for producing monoclonal antibodies are contemplated as well (e.g., viral or oncogenic transformation of B lymphocytes).

The preferred animal system for preparing hybridomas is the murine system. Hybridoma production in the mouse is a well-established procedure. Immunization protocols and techniques for isolation of immunized splenocytes for fusion are known in the art. Fusion partners (e.g., murine myeloma cells) and fusion procedures are also known.

Human monoclonal antibodies (mAbs) directed against human proteins can be generated using transgenic mice carrying the complete human immune system rather than-the mouse system. Splenocytes from the transgenic mice are immunized with the antigen of interest, which are used to produce hybridomas that secrete human mAbs with specific affinities for epitopes from a human protein. (See e.g., Wood et al., WO 91/00906, Kucherlapati et al., WO 91/10741; Lonberg et al., WO 92/03918; Kay et al., WO 92/03917 [each of which is herein incorporated by reference in its entirety]; N. Lonberg et al., Nature, 368:856-859 [1994]; L. L. Green et al., Nature Genet., 7:13-21 [1994]; S. L. Morrison et al., Proc. Nat. Acad. Sci. USA, 81:6851-6855 [1994]; Bruggeman et al., Immunol., 7:33-40 [1993]; Tuaillon et al., Proc. Nat. Acad. Sci. USA, 90:3720-3724 [1993]; and Bruggeman et al. Eur. J. Immunol., 21:1323-1326 [1991]).

Monoclonal antibodies can also be generated by other methods known to those skilled in the art of recombinant DNA technology. An alternative method, referred to as the “combinatorial antibody display” method, has been developed to identify and isolate antibody fragments having a particular antigen specificity, and can be utilized to produce monoclonal antibodies. (See e.g., Sastry et al., Proc. Nat. Acad. Sci. USA, 86:5728 [1989]; Huse et al., Science, 246:1275 [1989]; and Orlandi et al., Proc. Nat. Acad. Sci. USA, 86:3833 [1989]). After immunizing an animal with an immunogen as described above, the antibody repertoire of the resulting B-cell pool is cloned. Methods are generally known for obtaining the DNA sequence of the variable regions of a diverse population of immunoglobulin molecules by using a mixture of oligomer primers and the PCR. For instance, mixed oligonucleotide primers corresponding to the 5′ leader (signal peptide) sequences and/or framework 1 (FR1) sequences, as well as primer to a conserved 3′ constant region primer can be used for PCR amplification of the heavy and light chain variable regions from a number of murine antibodies. (See e.g., Larrick et al., Biotechniques, 11:152-156 [1991]). A similar strategy can also be used to amplify human heavy and light chain variable regions from human antibodies (See e.g., Larrick et al., Methods: Companion to Methods in Enzymology, 2:106-110 [1991]).

In one embodiment, RNA is isolated from B lymphocytes, for example, peripheral blood cells, bone marrow, or spleen preparations, using standard protocols (e.g., U.S. Pat. No. 4,683,292 [incorporated herein by reference in its entirety]; Orlandi, et al., Proc. Nat. Acad. Sci. USA, 86:3833-3837 [1989]; Sastry et al., Proc. Nat. Acad. Sci. USA, 86:5728-5732 [1989]; and Huse et al., Science, 246:1275 [1989]). First strand cDNA is synthesized using primers specific for the constant region of the heavy chain(s) and each of the Λ and λ light chains, as well as primers for the signal sequence. Using variable region PCR primers, the variable regions of both heavy and light chains are amplified, each alone or in combination, and ligated into appropriate vectors for further manipulation ingenerating the display packages. Oligonucleotide primers useful in amplification protocols may be unique or degenerate or incorporate inosine at degenerate positions. Restriction endonuclease recognition sequences may also be incorporated into the primers to allow for the cloning of the amplified fragment into a vector in a predetermined reading frame for expression.

The V-gene library cloned from the immunization-derived antibody repertoire can be expressed by a population of display packages, preferably derived from filamentous phage, to form an antibody display library. Ideally, the display package comprises a system that allows the sampling of very large variegated antibody display libraries, rapid sorting after each affinity separation round, and easy isolation of the antibody gene from purified display packages. In addition to commercially available kits for generating phage display libraries, examples of methods and reagents particularly amenable for use in generating a variegated antibody display library can be found in, for example, U.S. Pat. No. 5,223,409; WO 92/18619; WO 91/17271; WO 92/20791; WO 92/15679; WO 93/01288; WO 92/01047; WO 92/09690; WO 90/02809 [each of which is herein incorporated by refernce in its entirety]; Fuchs et al., Biol. Technology, 9:1370-1372 [1991]; Hay et al., Hum. Antibod. Hybridomas, 3:81-85 [1992]; Huse et al., Science, 46:1275-1281 [1989]; Hawkins et al., J. Mol. Biol., 226:889-896 [1992]; Clackson et al., Nature, 352:624-628 [1991]; Gram et al., Proc. Nat. Acad. Sci. USA, 89:3576-3580 [1992]; Garrad et al., Bio/Technolog, 2:1373-1377 [1991]; Hoogenboom et al., Nuc. Acid Res., 19:4133-4137 [1991]; and Barbas et al., Proc. Nat. Acad. Sci. USA, 88:7978

In certain embodiments, the V region domains of heavy and light chains can be expressed on the same polypeptide, joined by a flexible linker to form a single-chain Fv fragment, and the scFV gene subsequently cloned into the desired expression vector or phage genome.

As generally described in McCafferty et al., Nature, 348:552-554 (1990), complete V_(H) and V_(L) domains of an antibody, joined by a flexible linker (e.g., (Gly₄-Ser)₃) can be used to produce a single chain antibody which can render the display package separable based on antigen affinity. Isolated scFV antibodies immunoreactive with the antigen can subsequently be formulated into a pharmaceutical preparation for use in the subject method. CL10scFV, which binds FOLR2)(See, e.g., SEQ ID NO:120 and 121 and sequences having at least 809%, 90%, 95%, 99% and 100% identity thereto; US Pat. Publ. 20140010756, incorporated herein by reference in its entirety) is a non-limiting example of a scFv useful as a targeting unit in the present invention.

Once displayed on the surface of a display package (e.g., filamentous phage), the antibody library is screened with the target antigen, or peptide fragment thereof, to identify and isolate packages that express an antibody having specificity for the target antigen. Nucleic acid encoding the selected antibody can be recovered from the display package (e.g., from the phage genome) and subcloned into other expression vectors by standard recombinant DNA techniques.

Specific antibody molecules with high affinities for a surface protein can be made according to methods known to those in the art, e.g., methods involving screening of libraries U.S. Pat. Nos. 5,233,409 and 5,403,484 (both incorporated herein by reference in their entireties). Further, the methods of these libraries can be used in screens to obtain binding determinants that are mimetics of the structural determinants of antibodies.

In particular, the Fv binding surface of a particular antibody molecule interacts with its target ligand according to principles of protein-protein interactions, hence sequence data for V_(H) and V_(L) (the latter of which may be of the Λ or λ chain type) is the basis for protein engineering techniques known to those with skill in the art. Details of the protein surface that comprises the binding determinants can be obtained from antibody sequence in formation, by a modeling procedure using previously determined three-dimensional structures from other antibodies obtained from NMR studies or crytallographic data.

In one embodiment, a variegated peptide library is expressed by a population of display packages to form a peptide display library. Ideally, the display package comprises a system that allows the sampling of very large variegated peptide display libraries, rapid sorting after each affinity separation round, and easy isolation of the peptide-encoding gene from purified display packages. Peptide display libraries can be in, e.g., prokaryotic organisms and viruses, which can be amplified quickly, are relatively easy to manipulate, and which allows the creation of large number of clones. Preferred display packages include, for example, vegetative bacterial cells, bacterial spores, and most preferably, bacterial viruses (especially DNA viruses). However, the present invention also contemplates the use of eukaryotic cells, including yeast and their spores, as potential display packages. Phage display libraries are known in the art.

Other techniques include affinity chromatography with an appropriate “receptor,” e.g., a target antigen, followed by identification of the isolated binding agents or ligands by conventional techniques (e.g., mass spectrometry and NMR). Preferably, the soluble receptor is conjugated to a label (e.g., fluorophores, colorimetric enzymes, radioisotopes, or luminescent compounds) that can be detected to indicate ligand binding. Alternatively, immobilized compounds can be selectively released and allowed to diffuse through a membrane to interact with a receptor.

Combinatorial libraries of compounds can also be synthesized with “tags” to encode the identity of each member of the library. (See e.g., W. C. Still et al., WO 94/08051 incorporated herein by reference in its entirety). In general, this method features the use of inert but readily detectable tags that are attached to the solid support or to the compounds. When an active compound is detected, the identity of the compound is determined by identification of the unique accompanying tag. This tagging method permits the synthesis of large libraries of compounds that can be identified at very low levels among to total set of all compounds in the library.

The term modified antibody is also intended to include antibodies, such as monoclonal antibodies, chimeric antibodies, and humanized antibodies which have been modified by, for example, deleting, adding, or substituting portions of the antibody. For example, an antibody can be modified by deleting the hinge region, thus generating a monovalent antibody. Any modification is within the scope of the invention so long as the antibody has at least one antigen binding region specific.

Chimeric mouse-human monoclonal antibodies can be produced by recombinant DNA techniques known in the art. For example, a gene encoding the Fc constant region of a murine (or other species) monoclonal antibody molecule is digested with restriction enzymes to remove the region encoding the murine Fc, and the equivalent portion of a gene encoding a human Fc constant region is substituted. (See e.g., Robinson et al., PCT/US86/02269; European Patent Application 184,187; European Patent Application 171,496; European Patent Application 173,494; WO 86/01533; U.S. Pat. No. 4,816,567; European Patent Application 125,023 [each of which is herein incorporated by reference in its entirety]; Better et al., Science, 240:1041-1043 [1988]; Liu et al., Proc. Nat. Acad. Sci. USA, 84:3439-3443 [1987]; Liu et al., J. Immunol., 139:3521-3526 [1987]; Sun et al., Proc. Nat. Acad. Sci. USA, 84:214-218 [1987]; Nishimura et al., Canc. Res., 47:999-1005 [1987]; Wood et al., Nature, 314:446-449 [1985]; and Shaw et al., J. Natl. Cancer Inst., 80:1553-1559 [1988]).

The chimeric antibody can be further humanized by replacing sequences of the Fv variable region that are not directly involved in antigen binding with equivalent sequences from human Fv variable regions. General reviews of humanized chimeric antibodies are provided by S. L. Morrison, Science, 229:1202-1207 (1985) and by Oi et al., Bio. Techniques, 4:214 (1986). Those methods include isolating, manipulating, and expressing the nucleic acid sequences that encode all or part of immunoglobulin Fv variable regions from at least one of a heavy or light chain. Sources of such nucleic acid are well known to those skilled in the art and, for example, may be obtained from 7E3, an anti-GPII_(b)III_(a) antibody producing hybridoma. The recombinant DNA encoding the chimeric antibody, or fragment thereof, can then be cloned into an appropriate expression vector.

Suitable humanized antibodies can alternatively be produced by CDR substitution (e.g., U.S. Pat. No. 5,225,539 (incorporated herein by reference in its entirety); Jones et al., Nature, 321:552-525 [1986]; Verhoeyan et al., Science, 239:1534 [1988]; and Beidler et al., J. Immunol., 141:4053 [1988]). All of the CDRs of a particular human antibody may be replaced with at least a portion of a non-human CDR or only some of the CDRs may be replaced with non-human CDRs. It is only necessary to replace the number of CDRs required for binding of the humanized antibody to the Fc receptor.

An antibody can be humanized by any method that is capable of replacing at least a portion of a CDR of a human antibody with a CDR derived from a non-human antibody. The human CDRs may be replaced with non-human CDRs; using oligonucleotide site-directed mutagenesis.

Also within the scope of the invention are chimeric and humanized antibodies in which specific amino acids have been substituted, deleted or added. In particular, preferred humanized antibodies have amino acid substitutions in the framework region, such as to improve binding to the antigen. For example, in a humanized antibody having mouse CDRs, amino acids located in the human framework region can be replaced with the amino acids located at the corresponding positions in the mouse antibody. Such substitutions are known to improve binding of humanized antibodies to the antigen in some instances.

In some embodiments, the monoclonal antibody is a murine antibody or a fragment thereof. In other preferred embodiments, the monoclonal antibody is a bovine antibody or a fragment thereof. For example, the murine antibody can be produced by a hybridoma that includes a B cell obtained from a transgenic mouse having a genome comprising a heavy chain transgene and a light chain transgene fused to an immortalized cell. The antibodies can be of various isotypes, including, but not limited to: IgG (e.g., IgG1, IgG2, IgG2a, IgG2b, IgG2c, IgG3, IgG4); IgM; IgA1; IgA2; IgAsec; IgD; and IgE. In some preferred embodiments, the antibody is an IgG isotype. In other preferred embodiments, the antibody is an IgM isotype. The antibodies can be full-length (e.g., an IgG1, IgG2, IgG3, or IgG4 antibody) or can include only an antigen-binding portion (e.g., a Fab, F(ab′)2, Fv or a single chain Fv fragment).

In preferred embodiments, the immunoglobulin is a recombinant antibody (e.g., a chimeric or a humanized antibody), a subunit, or an antigen binding fragment thereof (e.g., has a variable region, or at least a complementarity determining region (CDR)).

In some embodiments, the immunoglobulin is monovalent (e.g., includes one pair of heavy and light chains, or antigen binding portions thereof). In other embodiments, the immunoglobulin is a divalent (e.g., includes two pairs of heavy and light chains, or antigen binding portions thereof).

In some embodiments, a system of hybridoma-like antibody preparation, developed by Neoclone (Madison, Wis.), is used in the production of monoclonal antibodies. Splenocytes from immunized mice are immortalized using a retrovector-mediated introduction of the abl-myc genes. On reintroduction into recipient mice one dominant immortalized B cell clone (plasmacytoma) outgrows all others and produces a monoclonal antibody in the ascitic fluid. The B cell clone can be harvested with the ascitic fluid that contains high concentration of monoclonal antibody. This process can be completed in 8-10 weeks.

It will be understood that the CDRs or variable domains from the novel nanobodies and/or single domain antibodies described above may be identified (See Table 1) and cloned and then inserted into a desired variable region or framework region to provide, for example, a humanized antibody, Fab, F(ab′)₂, Fab′ single chain antibody, Fv, single chain (scFv), mono-specific antibody, bi-specific antibody, tri-specific antibody, multivalent antibody, chimeric antibody, humanized antibody, human antibody, CDR-grafted antibody, microbody, intrabody (e.g., intracellular antibody), and/or de-fucosylated antibody and/or derivative thereof. Suitable CDR1, CDR2, and CDR3 sequences may be cloned, from example, any one of the nanobodies encoded by the following amino acid sequences: SEQ ID NOs: 30-56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, and 112 which bind to CD206 and SEQ ID NO: 122, which binds to FOLR2; or the following nucleic acid sequences: SEQ ID NOs:3, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107 and 111, which encode nanobodies which bind to CD206 and SEQ ID NO:123 which encodes a single domain antibody which binds to FOLR2.

It will be understood that antigen binding protein is may be identified with reference to the nucleotide and/or amino acid sequence corresponding to the variable and/or complementarity determining regions (“CDRs”) thereof. For instance, an exemplary antigen binding protein that is derived from, or is related to the nanobodies described above may comprise a heavy and/or a light chain that each comprise one or more constant and/or variable regions. The variable regions typically comprise one or more CDRs that in large part determine the binding specificity of the antibody. These antigen binding proteins may be identified by analysis of the nucleotide sequences encoding the variable regions. The antigen binding proteins may also be identified by analysis of the amino acid sequences of (e.g., which may be encoded by the nucleotide sequences) the variable regions.

Any of the variable regions or CDRs of the nanobodies described above (or variants thereof sharing at least 80% identity) may be combined with any other variable region and/or CDR in any order and/or combination to form hybrid and/or fusion binding agents and/or inserted into other heavy and/or light chain variable regions using standard techniques. These may be used in conjunction with any constant regions.

CDRs (complementarity-determining regions) are amino acid sequences from antibodies that are, at least in part, responsible for binding of an antibody to a specific target. It is understood by those of skill in the art that CDRs may be identified using any of several techniques and/or schemes. CDRs of the nanobodies shown herein may be identified using any of these techniques. For example, the CDRs of nanobodies may be identified as described above. The nanobodies have three CDR regions, each non-contiguous with the others (termed CDR1, CDR2, CDR3). The delineation of the FR and CDR sequences is often based on the IMGT unique numbering system for V-domains and V-like domains. (See, e.g., Lefranc M. P., C. Pommie, et al. (2003). “IMGT unique numbering for immunoglobulin and T cell receptor variable domains and Ig superfamily V-like domains.” Developmental and Comparative Immunology 27(1): 55-77.) Alternatively, the delineation of the FR and CDR sequences can be done by using the Kabat numbering system as applied to V_(H)H domains from Camelids in the article of Riechmann and Muyldermans. (See, e.g., Riechmann and Muyldermans J. Immunol. Methods 2000; 240: 185-195.) As will be known by the person skilled in the art, the nanobodies can in particular be characterized by the presence of one or more Camelidae hallmark residues in one or more of the framework sequences (according to Kabat numbering), as described, for example, in WO 08/020,079, on page 75, Table A-3, incorporated herein by reference).

A summary of various schemes, in part based on, for example, Kabat et al, “Sequences of Proteins of Immunological Interest,” 5th Ed., Public Health Service, National Institutes of Health, Bethesda, Md., NIH publication No. 91-3242 (1991), and Al-Lazikani et al, “Standard conformations for the canonical structures of immunoglobulins,” J. Mol. Biol. 273:927-948, 1997, is provided in Table 2 below:

TABLE 2 CDR Loop* Kabat AbM Chothia Contact L1 L24--L34 L24--L34 L24--L34 L30--L36 L2 L50--L56 L50--L56 L50--L56 L46--L55 L3 L89--L97 L89--L97 L89--L97 L89--L96 H1 H31-H35B H26--H35B H26--H32 . . . 34 H30--H35B (Kabat Numbering) H1 H31--H35 H26--H35 H26--H32 H30--H35 (Chotia Numbering) H2 H50--H65 H50--H58 H52--H56 H47--H58 H3 H95--H102 H95--H102 H95--H102 H93--H101 *L = light chain; H = heavy chain

CDRs may also be identified by following a set of rules such as those set forth in Table 3 below (as described on the world wide web at bioinforg.uk/absfficdrid):

TABLE 3 CDR*/Feature Typical Characteristic of Feature** CDR-L1 Start approximately residue 24 Residues before typically Cys Residues after typically Trp (e.g., Trp-Tyr-Gln, Trp-Leu-Gln, Trp-Phe-Gln, Trp-Tyr- Leu) Length 10 to 17 residues CDR-L2 Start typically 16 residues after the end of L1 Residues before typically Ile-Tyr, Val-Tyr, Ile-Lys, or Ile-Phe Length typically seven (7) residues CDR-L3 Start typically 33 residues after end of L2 Residues before typically Cys Length typically Phe-Gly-X-Gly (SEQ ID NO: 197) Residues after 7 to 11 residues CDR-H1 Start Approximately residue 26 (typically four (4) residues after a Cys) (Chothia/AbM definition); Kabat definition starts 5 residues later Residues before typically Cys-X-X-X (SEQ ID NO: 198) Residues after typically Trp (e.g., Trp-Val, Trp-Ile, Trp-Ala) Length 10 to 12 residues (AbM definition); Chothia definition excludes the last four (4) residues CDR-H2 Start typically 15 residues after the end of Kabat/AbM definition of CDR- H1 Residues before typically Leu-Glu-Trp-Ile-Gly (SEQ ID NO: 199) Residues after typically Lys/Arg-Leu/Ile/Val/ Phe/Thr/Ala-Thr/Ser/Ile/Ala (SEQ ID NO: 200) Length Kabat definition 16 to 19 residues; AbM (and recent Chothia) definition 9 to 12 residues CDR-H3 Start typically 33 residues after end of CDR-H2 (typically two (2) residues following a Cys) Residues before typically Cys-X-X (typically Cys-Ala-Arg) Residues after typically Trp-Gly-X-Gly (SEQ ID NO: 201) Length typically 3 to 25 residues *L = light chain; H = heavy chain; **X = any amino acid

These systems for identifying CDRs are merely exemplary and others may be suitable, as would be understood by one of ordinary skill in the art. CDRs thus identified may be used to identify suitable antigen binding proteins. These systems may be used to identify the CDR region of an antigen binding protein so that the CDRs of the present invention may be used to replace existing CDRs in the antigen binding protein or inserted into an appropriate framework or variable region of the antigen binding protein. Such CDRs may also be combined with one another in any order and/or combination to form hybrid and/or fusion binding agents and/or inserted into the other heavy and/or light chain variable regions using standard techniques. The amino acid sequences of the nanobodies, and/or any one or more fragments and/or derivatives thereof, may be encoded by any of several nucleic acid sequences. These nucleic acid sequences may also be used to identify and/or prepare (e.g., as nucleic acid molecules) suitable antigen binding proteins. For example, one of ordinary skill in the art may devise nucleotide sequences encoding any such amino acid sequences. Any of the nucleotide sequences and/or fragments and/or derivatives thereof, may be combined with one another in any order and/or combination to encode hybrid and/or fusion binding agents and/or inserted into the other nucleic acid sequences encoding light and/or heavy chain variable regions (and/or fragments and/or derivatives thereof).

The variable region sequences described herein (which may comprise fragments and/or derivatives thereof), including but not limited to the variable regions of the nanobodies described above (and/or fragments and/or derivatives thereof) an/or their corresponding nucleotide sequences (and/or fragments and/or derivatives thereof) may be used in combination with one or more amino acid sequences and/or nucleotide sequences encoding one or more constant chains (and/or a fragment and/or derivatives thereof) of an antibody molecule. For instance, the variable region amino acid sequences of the nanobodies may be joined to the constant regions of any antibody molecule of the same or a different species (e.g., human, goat, rat, sheep, chicken) of that from which the variable region amino acid sequence was derived. The constant regions may be derived from any of, for example, human (e.g., IgG (IgG1, IgG2, IgG3, IgG4), IgM, IgA (IgA1 and IgA2), IgD, and IgE), canine (e.g., IgG (IgGA, IgGB, IgGC, IgGD) IgA, IgD, IgE, and IgM), chicken (e.g., IgA, IgD, IgE, IgG, IgM, IgY), goat (e.g., IgG), mouse (e.g., IgA, IgG, IgD, IgE, IgM), pig (e.g., IgA, IgG, IgD, IgE, IgM), rat (e.g., IgA, IgG, IgD, IgE, IgM), feline (e.g., IgA, IgD, IgE, IgG, IgM) and/or a fragment and/or derivative thereof (e.g., as chimeric antibodies). Accordingly, the CDRs or variable regions of the nanobodies may be used to produce a humanized antibody, Fab, F(ab′)2, Fab′ single chain antibody, Fv, single chain (scFv), mono-specific antibody, bi-specific antibody, tri-specific antibody, multivalent antibody, chimeric antibody, humanized antibody, human antibody, CDR-grafted antibody, microbody, intrabody (e.g., intracellular antibody), and/or de-fucosylated antibody and/or derivative thereof, as is known in the art.

2. Immunostimulatory Agents

The fusion protein of the present invention may include a variety of different immunostimulatory agents. In some embodiments, the immunostimulatory agent in a fusion protein of the present invention is selected from an interleukin, an interferon, and a tumor necrosis factor.

The present invention is not limited to the use of any particular interleukins in the fusion proteins. In some embodiments, the interleukins are selected from IL-1(3, IL-2 (SEQ NO:22 and 118 (human na sequence), SEQ ID NO:23 and 119 (human aa sequence)), IL-7 (SEQ NO:131 (human na sequence), SEQ ID NO:132 (human aa sequence)), IL-8, IL-12, IL-15 (SEQ ID NO:7, 8, 116 (human na sequences), SEQ ID NO:9 and 117 (human aa sequence)), IL-17 (SEQ NO:18 and 136 (human na sequence), SEQ ID NO:19 and 137(human aa sequence)), IL-18 (SEQ NO:28 and 124 (mouse na sequence), SEQ ID NO:29 and 125 (mouse aa sequence)), IL-21 (SEQ ID NO:14 and 132 (mouse na sequence), SEQ ID NO:15 and 133 (mouse aa sequence), SEQ ID NO:16 (human na sequence), SEQ ID NO:17 (human aa sequence)), IL-23, IL-27 (SEQ NO:26 (mouse na sequence), SEQ ID NO:27 (mouse aa sequence)) and IL-33, functional subunits of the interleukins as well interleukin fusions such as IL15-RLI (SEQ NO:114 (na sequence), SEQ ID NO:115 (aa sequence)) which a fusion of IL15 to the sushi domain of IL-15Ra, and improved variants such as the hIL2-C125A human IL2 superagonist (SEQ NO:24 and 126 (na sequence), SEQ ID NO:25 and 127 (aa sequence)). The sequence information for exemplary interleukins, fusions and variants has been provided. It will be recognized by those of skill in the art that the sequences, for example, human or mouse sequences, for the remaining interleukins are known in the art and readily obtainable. In some embodiments, the interleukins used in the fusion proteins share at least 80%, 90%, 95%, 99%, or 100% identity with the interleukins identified above.

The present invention is not limited to the use of any particular interfereons in the fusion proteins. In some embodiments, the interferons are selected from IFNα1 (SEQ NO:12 and 134 (mouse na sequence), SEQ ID NO:13 and 135 (mouse aa sequence)), IFNα2, IFMβ1, IFNε1, IFNγ, IFNκ, and IFNω. The sequence information for exemplary interferons has been provided. It will be recognized by those of skill in the art that the sequences, for example, human or mouse sequences, for the remaining intererons are known in the art and readily obtainable. In some embodiments, the interferons used in the fusion proteins share at least 80%, 90%, 95%, 99%, or 100% identity with the interleukins identified above.

The present invention is not limited to the use of any particular tumor necrosis factors (TNFs) in the fusion proteins. In some embodiments, the TNFs are selected from TNFα (SEQ NO:20 and 128 (human na sequence), SEQ ID NO:21 and 129 (human aa sequence)), CD40L, EDA, FASL, LTA, LTB, RANKL, OX40L, TNFSF7, TNFSF8, TNFSF9, TNFSF12, TNFSF13, TNFSF13B, F18, TRAIL, BAFF, 4-1BBL, and 4-1BB. The sequence information for exemplary TNFs has been provided. It will be recognized by those of skill in the art that the sequences, for example, human or mouse sequences, for the remaining TNFs are known in the art and readily obtainable. In some embodiments, the TNFs used in the fusion proteins share at least 80%, 90%, 95%, 99%, or 100% identity with the interleukins identified above.

In some preferred embodiments, the immunostimulatory agent is IL-15 polypeptide (SEQ ID NO:7, 8, 116 (human na sequences), SEQ ID NO:9 and 117 (human aa sequence)) or IL15-IL15Ra fusion such as IL15-RLI (SEQ NO:114 (na sequence), SEQ ID NO:115 (aa sequence)) which a fusion of IL15 to the sushi domain of IL-15Ra. The subunits for the IL15-RLI fusion are preferably identified by SEQ ID NO:5 (IL15Ra sushi domain), SEQ ID NO:6 (Linker 20) and SEQ ID NO:7 (hIL15). IL15-RIL sequences and constructs are further described in US Pat. Publ. 20090238791, incorporated by reference herein in its entirety.

IL15 is a cytokine possessing all the qualities needed to elicit a potent immune response; it induces T cell activation and cell division, triggers cytotoxic effector pathways in T- and NK-cells, and supports T cell longevity. Based on these properties, IL15 has been considered one of the most attractive cytokine for tumor immunotherapy. Administration of IL15 has been evaluated in phase I/II trials that have documented that recombinant IL15 has an acceptable safety profile.

Using the targeting approach described herein, the present invention offers a means of selectively targeting IL15 to tumor-associated macrophages. Our approach allows one to exploit the full therapeutic potential of localized, intratumoral release of IL15 in a manner that has not been previously achieved.

Embodiments of the present invention provide fusion proteins and nucleic acids comprising such fusion proteins, comprising an immunostimulatory agent (e.g., IL15 polypeptide, IL15 receptor, or fragment thereof) fused to a targeting unit that targets the IL15 polypeptide to a tumor associated macrophage. In some embodiments, the targeting unit binds to CD206. In some embodiments, targeting unit is an immunoglobulin or fragment thereof that specifically binds to CD206. In some embodiments, the immunoglobulin is a single domain antibody (sdAb) fragment or a single chain variable fragments (scFv), although other antibody or antibody fragments are specifically contemplated. In some embodiments, the fusion polypeptide is 206RLI.

The present invention is not limited to particular immunostimulatory agents. Examples include, but are not limited to, IL-15, additional cytokines (e.g., interferon alpha, interferon gamma, interleukin-21, interleukin-17, interleukin-18, interleukin-27, TNF-α, interleukin 2, interleukin 7, interleukin 12); costimulatory ligands (e.g., 41bb, CD80, CD86); and antibody fragments with agonistic or antagonistic activity against immune checkpoints (e.g., anti-PD1, anti-CTLA4, etc).

The present invention is not limited to particular targeting units or targets. Examples include, but are not limited to, mannose receptor (CD206), folate receptor beta (FOLR2) and leugmain (LGMN). Other target structures on macrophages are identified though an evaluation of surface marker expression. In some embodiments, other stromal cell subsets such as tumor-associated fibroblasts substitute as the target cell type, and in this case, fibroblast activating protein (FAP), S100A4 and FSP-1 are examples of targets.

3. Fusions of Targeting Unit and Immunostimulatory Agents

In some embodiments, the present invention provides fusion proteins comprising a targeting unit in operable association with an immunostimulatory agent. Preferred targeting units and immunostimulatory agents are identified above. In some preferred embodiments, the targeting unit is an antigen binding protein, e.g., an antibody, immunoglobulin, or fragments thereof, nanobody, scFv, etc. In some preferred embodiments, the immunostimulaotry agent is a polypeptide selected from the group consisting of an interleukin, and interferon and a TNF.

Preferably, the targeting unit and the immunostimulaotry agent are operably connected to one another by a linker. As used herein, “linkers” are peptides of 1 to 50 amino acids length and are typically chosen or designed to be unstructured and flexible. These include, but are not limited to, synthetic peptides rich in Gly, Ser, Thr, Gln, Glu or further amino acids that are frequently associated with unstructured regions in natural proteins. (See, e.g., Dosztanyi Z., V. Csizmok, P. Tompa, and I. Simon (2005). IUPred: web server for the prediction of intrinsically unstructured regions of proteins based on estimated energy content. Bioinformatics (Oxford, England), 21(16), 3433-4.) Non-limiting examples of suitable linker sequences are described in the Example section, and include (G₄S)₃ (GGGGSGGGGSGGGGS; SEQ ID NO:110), llama IgG2 hinge (AHHSEDPSSKAPKAPMA; SEQ ID NO:109, see also, SEQ ID NO:4 and SEQ ID NO:113) or human IgA hinge (SPSTPPTPSPSTPPAS SEQ ID NO:147) linkers. It will be readily understood that other linkers may be utilized.

The present invention is not limited to any particular fusion protein comprising a targeting unit in operable association with an immunostimulatory agent. It will understood that the targeting units described above may be paired with any of the immunostimulatory agents. Table 4 provides non-limiting examples of fusion proteins of the present invention.

TABLE 4 SEQUENCE TYPE IMMUNO- SEQ ID AMINO ACID (AA) TARGETING STIMULATORY NO: NUCLEIC ACID (NA) UNIT AGENT 1 NA CD206 nanobody IL15-RLI 2 AA CD206 nanobody IL15-RLI 138 NA CD206 nanobody hIL15 139 NA CD206 nanobody hIL2 140 NA CL10scFV IL15-RLI 141 NA FOLR2sdAB IL15-RLI 142 NA FOLR2sdAB hIL15 143 NA FOLR2sdAB hIL2 144 NA CD206 nanobody IL15-RLI 145 NA CD206 nanobody hIL15 146 NA CD206 nanobody hIL2 153 NA CD206 nanobody hIL18 154 NA CD206 nanobody hIL17 155 NA CD206 nanobody hTNFa 156 NA CD206 nanobody hIFNa 157 NA CD206 nanobody hIL21 158 NA FOLR2sdAB hIL18 159 NA FOLR2sdAB hIL17 160 NA FOLR2sdAB hTNFa 161 NA FOLR2sdAB hIFNa 162 NA FOLR2sdAB hIL21 163 NA CD206 nanobody h41BBL 164 NA FOLR2sdAB h41BBL 165 NA CD206 nanobody hOX40L 166 NA FOLR2sdAB hOX40L 167 NA CD206 nanobody hCD40L 168 NA FOLR2sdAB hCD40L 169 NA CD206 nanobody hIL17 170 NA FOLR2sdAB hIL17 The fusion proteins of the present invention are not limited to the particular sequences disclosed in Table 4. In some embodiments, the present invention encompasses variants of the identified sequences. For example, in some embodiments, the present invention provides variants of the sequences listed in table 4 that have at least 80%, 90%, 95%, 99% or 100% identity to the fusion proteins (i.e., the amino acid sequences) encoded by the sequences.

4. Vectors and Expression

In some embodiments, the present invention provides nucleic acids encoding the antigen binding proteins and fusion proteins described above. In some embodiments, the present invention provides vectors comprising the nucleic acids, as well as host cells comprising the vectors that are utilized for expression of the antigen binding proteins and/or fusion proteins. In some embodiments, the present invention provides vectors and recombinant expression systems for expressing peptides and constructs described herein. The present invention is not limited to particular expression vectors. Exemplary vectors and expression methods are described herein.

In some embodiments, peptides are expressed using any suitable vector and expression system. In some embodiments, peptides are expressed in bacterial or eukaryotic expression vectors (e.g., commercially available vectors). In some embodiments, peptides are expressed in retroviral (e.g., adeno, adeno-associated, or lenti-viral vectors). Suitable vectors are introduced into suitable host cells (e.g., bacterial or eukaryotic host cells), expression is induced, and peptides are isolated using any suitable method.

The peptides, polypeptides, and proteins of the present invention may be produced by recombinant techniques. Thus, for example, a polynucleotide encoding a peptide, polypeptide or protein of the present invention may be included in any one of a variety of expression vectors for expressing a polypeptide. In some embodiments of the present invention, vectors include, but are not limited to, chromosomal, nonchromosomal and synthetic DNA sequences (e.g., derivatives of SV40, bacterial plasmids, phage DNA; baculovirus, yeast plasmids, vectors derived from combinations of plasmids and phage DNA, retroviral vectors and viral DNA such as vaccinia, adenovirus, fowl pox virus, and pseudorabies). It is contemplated that any vector may be used as long as it is replicable and viable in the host.

In particular, some embodiments of the present invention provide recombinant constructs comprising one or more of the sequences as broadly described above. In some embodiments of the present invention, the constructs comprise a vector, such as a plasmid or viral vector, into which a sequence of the invention has been inserted, in a forward or reverse orientation. In still other embodiments, the heterologous structural sequence is assembled in appropriate phase with translation initiation and termination sequences. In preferred embodiments of the present invention, the appropriate DNA sequence is inserted into the vector using any of a variety of procedures. In general, the DNA sequence is inserted into an appropriate restriction endonuclease site(s) by procedures known in the art.

Large numbers of suitable vectors are known to those of skill in the art, and are commercially available. Such vectors include, but are not limited to, the following vectors: 1) Bacterial—pQE70, pQE60, pQE-9 (Qiagen), pBS, pD10, phagescript, psiX174, pbluescript SK, pBSKS, pNH8A, pNH16a, pNH18A, pNH46A (Stratagene); ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5 (Pharmacia); 2) Eukaryotic—pWLNEO, pSV2CAT, pOG44, PXT1, pSG (Stratagene) pSVK3, pBPV, pMSG, pSVL (Pharmacia); and 3) Baculovirus—pPbac and pMbac (Stratagene). Any other plasmid or vector may be used as long as they are replicable and viable in the host. In some preferred embodiments of the present invention, mammalian expression vectors comprise an origin of replication, a suitable promoter and enhancer, and also any necessary ribosome binding sites, polyadenylation sites, splice donor and acceptor sites, transcriptional termination sequences, and 5′ flanking non-transcribed sequences. In other embodiments, DNA sequences derived from the SV40 splice, and polyadenylation sites may be used to provide the required non-transcribed genetic elements.

In certain embodiments of the present invention, the DNA sequence in the expression vector is operatively linked to an appropriate expression control sequence(s) (promoter) to direct mRNA synthesis. Promoters useful in the present invention include, but are not limited to, the LTR or SV40 promoter, the E. coli lac or trp, the phage lambda PL and PR, T3 and T7 promoters, and the cytomegalovirus (CMV) immediate early, herpes simplex virus (HSV) thymidine kinase, and mouse metallothionein-I promoters and other promoters known to control expression of gene in prokaryotic or eukaryotic cells or their viruses. In other embodiments of the present invention, recombinant expression vectors include origins of replication and selectable markers permitting transformation of the host cell (e.g., dihydrofolate reductase or neomycin resistance for eukaryotic cell culture, or tetracycline or ampicillin resistance in E. coli).

In some embodiments of the present invention, transcription of the DNA encoding the polypeptides of the present invention by higher eukaryotes is increased by inserting an enhancer sequence into the vector. Enhancers are cis-acting elements of DNA, usually about from 10 to 300 bp that act on a promoter to increase its transcription. Enhancers useful in the present invention include, but are not limited to, the SV40 enhancer on the late side of the replication origin bp 100 to 270, a cytomegalovirus early promoter enhancer, the polyoma enhancer on the late side of the replication origin, and adenovirus enhancers.

In other embodiments, the expression vector also contains a ribosome binding site for translation initiation and a transcription terminator. In still other embodiments of the present invention, the vector may also include appropriate sequences for amplifying expression.

In some embodiments, retroviral vectors are utilized for expression in a suitable host cell. The production of a recombinant retroviral vector carrying a gene of interest is typically achieved in two stages. First, the gene of interest is inserted into a retroviral vector which contains the sequences necessary for the efficient expression of the gene of interest (including promoter and/or enhancer elements which may be provided by the viral long terminal repeats [LTRs] or by an internal promoter/enhancer and relevant splicing signals), sequences required for the efficient packaging of the viral RNA into infectious virions (e.g., the packaging signal [Psi], the tRNA primer binding site [−PBS], the 3′ regulatory sequences required for reverse transcription [+PBS] and the viral LTRs). The LTRs contain sequences required for the association of viral genomic RNA, reverse transcriptase and integrase functions, and sequences involved in directing the expression of the genomic RNA to be packaged in viral particles. For safety reasons, many recombinant retroviral vectors lack functional copies of the genes that are essential for viral replication (these essential genes are either deleted or disabled); the resulting virus is said to be replication defective or incompetent.

Second, following the construction of the recombinant vector, the vector DNA is introduced into a packaging cell line. Packaging cell lines provide viral proteins required in trans for the packaging of the viral genomic RNA into viral particles having the desired host range (i.e., the viral-encoded gag, pol and env proteins). The host range is controlled, in part, by the type of envelope gene product expressed on the surface of the viral particle. Packaging cell lines may express ecotrophic, amphotropic or xenotropic envelope gene products. Alternatively, the packaging cell line may lack sequences encoding a viral envelope (env) protein. In this case the packaging cell line will package the viral genome into particles that lack a membrane-associated protein (e.g., an env protein). In order to produce viral particles containing a membrane associated protein that will permit entry of the virus into a cell, the packaging cell line containing the retroviral sequences is transfected with sequences encoding a membrane-associated protein (e.g., the G protein of vesicular stomatitis virus [VSV]). The transfected packaging cell will then produce viral particles that contain the membrane-associated protein expressed by the transfected packaging cell line; these viral particles, which contain viral genomic RNA derived from one virus encapsidated by the envelope proteins of another virus are said to be pseudotyped virus particles.

Commonly used recombinant retroviral vectors are derived from the amphotropic Moloney murine leukemia virus (MoMLV) (Miller and Baltimore, Mol. Cell. Biol., 6:2895 [1986]). The MoMLV system has several advantages: 1) this specific retrovirus can infect many different cell types, 2) established packaging cell lines are available for the production of recombinant MoMLV viral particles and 3) the transferred genes are permanently integrated into the target cell chromosome. The established MoMLV vector systems comprise a DNA vector containing a small portion of the retroviral sequence (the viral long terminal repeat or “LTR” and the packaging or “psi” signal) and a packaging cell line. The gene to be transferred is inserted into the DNA vector. The viral sequences present on the DNA vector provide the signals necessary for the insertion or packaging of the vector RNA into the viral particle and for the expression of the inserted gene. The packaging cell line provides the viral proteins required for particle assembly (Markowitz et al., J. Virol., 62:1120 [1988]).

Other commonly used retrovectors are derived from lentiviruses including, but not limited to, human immunodeficiency virus (HIV) or feline immunodeficiency virus (Hy). Lentivirus vectors have the advantage of being able to infect non replicating cells.

The low titer and inefficient infection of certain cell types by retro vectors has been overcome by the use of pseudotyped retroviral vectors which contain the G protein of VSV as the membrane associated protein. Unlike retroviral envelope proteins which bind to a specific cell surface protein receptor to gain entry into a cell, the VSV G protein interacts with a phospholipid component of the plasma membrane (Mastromarino et al., J. Gen. Virol., 68:2359 [1977]). Because entry of VSV into a cell is not dependent upon the presence of specific protein receptors, VSV has an extremely broad host range. Pseudotyped retroviral vectors bearing the VSV G protein have an altered host range characteristic of VSV (i.e., they can infect almost all species of vertebrate, invertebrate and insect cells). Importantly, VSV G-pseudotyped retroviral vectors can be concentrated 2000-fold or more by ultracentrifugation without significant loss of infectivity (Burns et al., Proc. Natl. Acad. Sci. USA, 90:8033 [1993]).

The VSV G protein has also been used to pseudotype retroviral vectors based upon the human immunodeficiency virus (HIV) (Naldini et al., Science 272:263 [1996]). Thus, the VSV G protein may be used to generate a variety of pseudotyped retroviral vectors and is not limited to vectors based on MoMLV.

The majority of retroviruses can transfer or integrate a double-stranded linear form of the virus (the provirus) into the genome of the recipient cell only if the recipient cell is cycling (i.e., dividing) at the time of infection. Retroviruses that have been shown to infect dividing cells exclusively, or more efficiently, include MLV, spleen necrosis virus, Rous sarcoma virus human immunodeficiency virus, and other lentiviral vectors.

In a further embodiment, the present invention provides host cells containing the above-described constructs. In some embodiments of the present invention, the host cell is a higher eukaryotic cell (e.g., a mammalian or insect cell). In other embodiments of the present invention, the host cell is a lower eukaryotic cell (e.g., a yeast cell). In still other embodiments of the present invention, the host cell can be a prokaryotic cell (e.g., a bacterial cell). Specific examples of host cells include, but are not limited to, Escherichia coli, Salmonella typhimurium, Bacillus subtilis, and various species within the genera Pseudomonas, Streptomyces, and Staphylococcus, as well as Saccharomycees cerivisiae, Schizosaccharomycees pombe, Drosophila S2 cells, Spodoptera Sf9 cells, Chinese hamster ovary (CHO) cells, COS-7 lines of monkey kidney fibroblasts, (Gluzman, Cell 23:175 (1981)), C127, 3T3, 293, 293T, HeLa and BHK cell lines, T-1 (tobacco cell culture line), root cell and cultured roots in rhizosecretion (Gleba et al., (1999) Proc Natl Acad Sci USA 96:5973-5977).

The constructs in host cells can be used in a conventional manner to produce the gene product encoded by the recombinant sequence. In some embodiments, introduction of the construct into the host cell can be accomplished by calcium phosphate transfection, DEAE-Dextran mediated transfection, or electroporation (See e.g., Davis et al. (1986) Basic Methods in Molecular Biology). Alternatively, in some embodiments of the present invention, the polypeptides of the invention can be synthetically produced by conventional peptide synthesizers.

Proteins can be expressed in mammalian cells, yeast, bacteria, or other cells under the control of appropriate promoters. Cell-free translation systems can also be employed to produce such proteins using RNAs derived from the DNA constructs of the present invention. Appropriate cloning and expression vectors for use with prokaryotic and eukaryotic hosts are described by Sambrook, et al. (1989) Molecular Cloning: A Laboratory Manual, Second Edition, Cold Spring Harbor, N.Y.

In some embodiments of the present invention, following transformation of a suitable host strain and growth of the host strain to an appropriate cell density, the selected promoter is induced by appropriate means (e.g., temperature shift or chemical induction) and cells are cultured for an additional period. In other embodiments of the present invention, cells are typically harvested by centrifugation, disrupted by physical or chemical means, and the resulting crude extract retained for further purification. In still other embodiments of the present invention, microbial cells employed in expression of proteins can be disrupted by any convenient method, including freeze-thaw cycling, sonication, mechanical disruption, or use of cell lysing agents.

5. Formulations

Where clinical applications are contemplated, in some embodiments of the present invention, the fusion proteins are prepared as part of a pharmaceutical composition in a form appropriate for the intended application. Generally, this entails preparing compositions that are essentially free of pyrogens, as well as other impurities that could be harmful to humans or animals. However, in some embodiments of the present invention, a fusion protein composition formulation may be administered using one or more of the routes described herein.

In some embodiments, the fusion protein compositions are used in conjunction with appropriate salts and buffers to render delivery of the compositions in a stable manner to allow for uptake by target cells. Buffers also are employed when the compositions are introduced into a patient. Aqueous compositions comprise an effective amount of composition dispersed in a pharmaceutically acceptable carrier or aqueous medium. Such compositions also are referred to as inocula.

The phrase “pharmaceutically or pharmacologically acceptable” refer to molecular entities and compositions that do not produce adverse, allergic, or other untoward reactions when administered to an animal or a human. As used herein, “pharmaceutically acceptable carrier” includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents and the like. Except insofar as any conventional media or agent is incompatible with the vectors or cells of the present invention, its use in therapeutic compositions is contemplated. Supplementary active ingredients may also be incorporated into the compositions.

In some embodiments of the present invention, the active compositions include classic pharmaceutical preparations. Administration of these compositions according to the present invention is via any common route so long as the target tissue is available via that route. This includes oral, nasal, buccal, rectal, vaginal or topical. Alternatively, administration may be by orthotopic, intradermal, subcutaneous, intramuscular, intraperitoneal or intravenous injection.

The compositions may also be administered parenterally or intraperitoneally or intratumorally. Solutions of the active compounds as free base or pharmacologically acceptable salts are prepared in water suitably mixed with a surfactant, such as hydroxypropylcellulose. Dispersions can also be prepared in glycerol, liquid polyethylene glycols, and mixtures thereof and in oils. Under ordinary conditions of storage and use, these preparations contain a preservative to prevent the growth of microorganisms.

The pharmaceutical forms suitable for injectable use include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. The carrier may be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyethylene glycol, and the like), suitable mixtures thereof, and vegetable oils. The proper fluidity can be maintained, for example, by the use of a coating, such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. The prevention of the action of microorganisms can be brought about by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, thimerosal, and the like. In many cases, it may be preferable to include isotonic agents, for example, sugars or sodium chloride. Prolonged absorption of the injectable compositions can be brought about by the use in the compositions of agents delaying absorption, for example, aluminum monostearate and gelatin.

Sterile injectable solutions are prepared by incorporating the active compounds in the required amount in the appropriate solvent with various of the other ingredients enumerated above, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the various sterilized active ingredients into a sterile vehicle which contains the basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum-drying and freeze-drying techniques which yield a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof.

Upon formulation, compositions are administered in a manner compatible with the dosage formulation and in such amount as is therapeutically effective. The formulations are easily administered in a variety of dosage forms such as injectable solutions, drug release capsules and the like. For parenteral administration in an aqueous solution, for example, the solution is suitably buffered, if necessary, and the liquid diluent first rendered isotonic with sufficient saline or glucose. These particular aqueous solutions are especially suitable for intravenous, intramuscular, subcutaneous and intraperitoneal administration. For example, one dosage could be dissolved in 1 ml of isotonic NaCl solution and either added to 1000 ml of hypodermoclysis fluid or injected at the proposed site of infusion, (see for example, “Remington's Pharmaceutical Sciences” 15th Edition, pages 1035-1038 and 1570-1580). In some embodiments of the present invention, the active particles or agents are formulated within a therapeutic mixture to comprise about 0.0001 to 1.0 milligrams, or about 0.001 to 0.1 milligrams, or about 0.1 to 1.0 or even about 10 milligrams per dose or so. Multiple doses may be administered.

Additional formulations that are suitable for other modes of administration include vaginal suppositories and pessaries. A rectal pessary or suppository may also be used. Suppositories are solid dosage forms of various weights and shapes, usually medicated, for insertion into the rectum, vagina or the urethra. After insertion, suppositories soften, melt or dissolve in the cavity fluids. In general, for suppositories, traditional binders and carriers may include, for example, polyalkylene glycols or triglycerides; such suppositories may be formed from mixtures containing the active ingredient in the range of 0.5% to 10%, preferably 1%-2%. Vaginal suppositories or pessaries are usually globular or oviform and weighing about 5 g each. Vaginal medications are available in a variety of physical forms, e.g., creams, gels or liquids, which depart from the classical concept of suppositories. In addition, suppositories may be used in connection with colon cancer.

“Treating” within the context of the instant invention, means an alleviation, in whole or in part, of symptoms associated with a disorder or disease, or slowing, inhibiting or halting of further progression or worsening of those symptoms, or prevention or prophylaxis of the disease or disorder in a subject at risk for developing the disease or disorder. Thus, e.g., treating cancer may include inhibiting or preventing the metastasis of the cancer, a reduction in the speed and/or number of the metastasis, a reduction in tumor volume of the metastasized cancer, a complete or partial remission of the metastasized cancer or any other therapeutic benefit. As used herein, a “therapeutically effective amount” of a compound of the invention refers to an amount of the compound that alleviates, in whole or in part, symptoms associated with a disorder or disease, or slows, inhibits or halts further progression or worsening of those symptoms, or prevents or provides prophylaxis for the disease or disorder in a subject at risk for developing the disease or disorder.

A subject is any animal that can benefit from the administration of a compound as described herein. In some embodiments, the subject is a mammal, for example, a human, a primate, a dog, a cat, a horse, a cow, a pig, a rodent, such as for example a rat or mouse. Typically, the subject is a human.

A therapeutically effective amount of a compound as described herein used in the present invention may vary depending upon the route of administration and dosage form. Effective amounts of invention compounds typically fall in the range of about 0.001 up to 100 mg/kg/day, and more typically in the range of about 0.05 up to 10 mg/kg/day. Typically, the compound or compounds used in the instant invention are selected to provide a formulation that exhibits a high therapeutic index. The therapeutic index is the dose ratio between toxic and therapeutic effects which can be expressed as the ratio between LD50 and ED50. The LD50 is the dose lethal to 50% of the population and the ED50 is the dose therapeutically effective in 50% of the population. The LD50 and ED50 are determined by standard pharmaceutical procedures in animal cell cultures or experimental animals.

The instant invention also provides for pharmaceutical compositions and medicaments which may be prepared by combining one or more compounds described herein, pharmaceutically acceptable salts thereof, stereoisomers thereof, tautomers thereof, or solvates thereof, with pharmaceutically acceptable carriers, excipients, binders, diluents or the like to inhibit or treat primary and/or metastatic prostate cancers. Such compositions can be in the form of, for example, granules, powders, tablets, capsules, syrup, suppositories, injections, emulsions, elixirs, suspensions or solutions. The instant compositions can be formulated for various routes of administration, for example, by oral, parenteral, topical, rectal, nasal, or via implanted reservoir. Parenteral or systemic administration includes, but is not limited to, subcutaneous, intravenous, intraperitoneal, and intramuscular injections. The following dosage forms are given by way of example and should not be construed as limiting the instant invention.

For oral, buccal, and sublingual administration, powders, suspensions, granules, tablets, pills, capsules, gelcaps, and caplets are acceptable as solid dosage forms. These can be prepared, for example, by mixing one or more compounds of the instant invention, or pharmaceutically acceptable salts or tautomers thereof, with at least one additive such as a starch or other additive. Suitable additives are sucrose, lactose, cellulose sugar, mannitol, maltitol, dextran, starch, agar, alginates, chitins, chitosans, pectins, tragacanth gum, gum arabic, gelatins, collagens, casein, albumin, synthetic or semi-synthetic polymers or glycerides. Optionally, oral dosage forms can contain other ingredients to aid in administration, such as an inactive diluent, or lubricants such as magnesium stearate, or preservatives such as paraben or sorbic acid, or antioxidants such as ascorbic acid, tocopherol or cysteine, a disintegrating agent, binders, thickeners, buffers, sweeteners, flavoring agents or perfuming agents. Tablets and pills may be further treated with suitable coating materials known in the art.

Liquid dosage forms for oral administration may be in the form of pharmaceutically acceptable emulsions, syrups, elixirs, suspensions, and solutions, which may contain an inactive diluent, such as water. Pharmaceutical formulations and medicaments may be prepared as liquid suspensions or solutions using a sterile liquid, such as, but not limited to, an oil, water, an alcohol, and combinations of these. Pharmaceutically suitable surfactants, suspending agents, emulsifying agents, may be added for oral or parenteral administration.

As noted above, suspensions may include oils. Such oils include, but are not limited to, peanut oil, sesame oil, cottonseed oil, com oil and olive oil. Suspension preparations may also contain esters of fatty acids such as ethyl oleate, isopropyl myristate, fatty acid glycerides and acetylated fatty acid glycerides. Suspension formulations may include alcohols, such as, but not limited to, ethanol, isopropyl alcohol, hexadecyl alcohol, glycerol and propylene glycol. Ethers, such as but not limited to, poly(ethyleneglycol), petroleum hydrocarbons such as mineral oil and petrolatum; and water may also be used in suspension formulations.

Injectable dosage forms generally include aqueous suspensions or oil suspensions which may be prepared using a suitable dispersant or wetting agent and a suspending agent. Injectable forms may be in solution phase or in the form of a suspension, which is prepared with a solvent or diluent. Acceptable solvents or vehicles include sterilized water, Ringer's solution, or an isotonic aqueous saline solution. Alternatively, sterile oils may be employed as solvents or suspending agents. Typically, the oil or fatty acid is non-volatile, including natural or synthetic oils, fatty acids, mono-, di- or tri-glycerides.

For injection, the pharmaceutical formulation and/or medicament may be a powder suitable for reconstitution with an appropriate solution as described above. Examples of these include, but are not limited to, freeze dried, rotary dried or spray dried powders, amorphous powders, granules, precipitates, or particulates. For injection, the formulations may optionally contain stabilizers, pH modifiers, surfactants, bioavailability modifiers and combinations of these.

For rectal administration, the pharmaceutical formulations and medicaments may be in the form of a suppository, an ointment, an enema, a tablet or a cream for release of compound in the intestines, sigmoid flexure and/or rectum. Rectal suppositories are prepared by mixing one or more compounds of the instant invention, or pharmaceutically acceptable salts or tautomers of the compound, with acceptable vehicles, for example, cocoa butter or polyethylene glycol, which is present in a solid phase at normal storing temperatures, and present in a liquid phase at those temperatures suitable to release a drug inside the body, such as in the rectum. Oils may also be employed in the preparation of formulations of the soft gelatin type and suppositories. Water, saline, aqueous dextrose and related sugar solutions, and glycerols may be employed in the preparation of suspension formulations which may also contain suspending agents such as pectins, carbomers, methyl cellulose, hydroxypropyl cellulose or carboxymethyl cellulose, as well as buffers and preservatives.

Compounds of the invention may be administered to the lungs by inhalation through the nose or mouth. Suitable pharmaceutical formulations for inhalation include solutions, sprays, dry powders, or aerosols containing any appropriate solvents and optionally other compounds such as, but not limited to, stabilizers, antimicrobial agents, antioxidants, pH modifiers, surfactants, bioavailability modifiers and combinations of these. Formulations for inhalation administration contain as excipients, for example, lactose, polyoxyethylene-9-lauryl ether, glycocholate and deoxycholate. Aqueous and nonaqueous aerosols are typically used for delivery of inventive compounds by inhalation.

Ordinarily, an aqueous aerosol is made by formulating an aqueous solution or suspension of the compound together with conventional pharmaceutically acceptable carriers and stabilizers. The carriers and stabilizers vary with the requirements of the particular compound, but typically include nonionic surfactants (TWEENs, Pluronics, or polyethylene glycol), innocuous proteins like serum albumin, sorbitan esters, oleic acid, lecithin, amino acids such as glycine, buffers, salts, sugars or sugar alcohols. Aerosols generally are prepared from isotonic solutions. A nonaqueous suspension (e.g., in a fluorocarbon propellant) can also be used to deliver compounds of the invention.

Aerosols containing compounds for use according to the present invention are conveniently delivered using an inhaler, atomizer, pressurized pack or a nebulizer and a suitable propellant, e.g., without limitation, pressurized dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, nitrogen, air, or carbon dioxide. In the case of a pressurized aerosol, the dosage unit may be controlled by providing a valve to deliver a metered amount. Capsules and cartridges of, for example, gelatin for use in an inhaler or insufflator may be formulated containing a powder mix of the compound and a suitable powder base such as lactose or starch.

Delivery of aerosols of the present invention using sonic nebulizers is advantageous because nebulizers minimize exposure of the agent to shear, which can result in degradation of the compound.

For nasal administration, the pharmaceutical formulations and medicaments may be a spray, nasal drops or aerosol containing an appropriate solvent(s) and optionally other compounds such as, but not limited to, stabilizers, antimicrobial agents, antioxidants, pH modifiers, surfactants, bioavailability modifiers and combinations of these. For administration in the form of nasal drops, the compounds maybe formulated in oily solutions or as a gel. For administration of nasal aerosol, any suitable propellant may be used including compressed air, nitrogen, carbon dioxide, or a hydrocarbon based low boiling solvent.

Dosage forms for the topical (including buccal and sublingual) or transdermal administration of compounds of the invention include powders, sprays, ointments, pastes, creams, lotions, gels, solutions, and patches. The active component may be mixed under sterile conditions with a pharmaceutically-acceptable carrier or excipient, and with any preservatives, or buffers, which may be required. Powders and sprays can be prepared, for example, with excipients such as lactose, talc, silicic acid, aluminum hydroxide, calcium silicates and polyamide powder, or mixtures of these substances. The ointments, pastes, creams and gels may also contain excipients such as animal and vegetable fats, oils, waxes, paraffins, starch, tragacanth, cellulose derivatives, polyethylene glycols, silicones, bentonites, silicic acid, talc and zinc oxide, or mixtures thereof.

Transdermal patches have the added advantage of providing controlled delivery of a compound of the invention to the body. Such dosage forms can be made by dissolving or dispersing the agent in the proper medium. Absorption enhancers can also be used to increase the flux of the inventive compound across the skin. The rate of such flux can be controlled by either providing a rate controlling membrane or dispersing the compound in a polymer matrix or gel.

Besides those representative dosage forms described above, pharmaceutically acceptable excipients and carriers are generally known to those skilled in the art and are thus included in the instant invention. Such excipients and carriers are described, for example, in

“Remington's Pharmaceutical Sciences” Mack Pub. Co., New Jersey (1991), which is incorporated herein by reference.

The formulations of the invention may be designed to be short-acting, fast-releasing, long-acting, and sustained-releasing as described below. Thus, the pharmaceutical formulations may also be formulated for controlled release or for slow release.

The instant compositions may also comprise, for example, micelles or liposomes, or some other encapsulated form, or may be administered in an extended release form to provide a prolonged storage and/or delivery effect. Therefore, the pharmaceutical formulations and medicaments may be compressed into pellets or cylinders and implanted intramuscularly or subcutaneously as depot injections or as implants such as stents. Such implants may employ known inert materials such as silicones and biodegradable polymers.

Specific dosages may be adjusted depending on conditions of disease, the age, body weight, general health conditions, sex, and diet of the subject, dose intervals, administration routes, excretion rate, and combinations of drugs. Any of the above dosage forms containing effective amounts are well within the bounds of routine experimentation and therefore, well within the scope of the instant invention.

In some embodiments of the present invention, methods and compositions are provided for the treatment of tumors and. In some embodiments, the cancer is, for example, lung cancer, breast cancer, pancreatic cancer, prostate cancer, melanoma or multiple myeloma.

Other cell proliferative disorders, or cancers, contemplated to be treatable with the methods of the present invention include human sarcomas and carcinomas, including, but not limited to, fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteogenic sarcoma, chordoma, angiosarcoma, endotheliosarcoma, lymphangiosarcoma, Ewing's tumor, lymphangioendotheliosarcoma, synovioma, mesothelioma, leiomyosarcoma, rhabdomyosarcoma, colon carcinoma, pancreatic cancer, breast cancer, ovarian cancer, prostate cancer, squamous cell carcinoma, basal cell carcinoma, adenocarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillary carcinoma, papillary adenocarcinomas, cystadenocarcinoma, medullary carcinoma, bronchogenic carcinoma, renal cell carcinoma, hepatoma, bile duct carcinoma, choriocarcinoma, seminoma, embryonal carcinoma, Wilms' tumor, cervical cancer, testicular tumor, lung carcinoma, small cell lung carcinoma, bladder carcinoma, epithelial carcinoma, glioma, astrocytoma, medulloblastoma, craniopharyngioma, ependymoma, pinealoma, hemangioblastoma, acoustic neuroma, oligodendroglioma, meningioma, melanoma, neuroblastoma, retinoblastoma, leukemias, acute lymphocytic leukemia and acute myelocytic leukemia (myeloblastic, promyelocytic, myelomonocytic, monocytic and erythroleukemia), chronic leukemia (chronic myelocytic (granulocytic) leukemia and chronic lymphocytic leukemia), polycythemia vera, lymphoma (Hodgkin's disease and non-Hodgkin's disease), multiple myeloma, Waldenstrom's macroglobulinemia, and heavy chain disease.

Tumor cell resistance to chemotherapeutic agents represents a major problem in clinical oncology. In some embodiments, compositions and methods of the present invention provide means of ameliorating this problem by effectively administering a combined therapy approach. However, it should be noted that traditional combination therapy may be employed in combination with the compositions of the present invention. For example, in some embodiments of the present invention, immunotherapies are used before, after, or in combination with the traditional therapies.

To kill cells, inhibit cell growth, or metastasis, or angiogenesis, or otherwise reverse or reduce the malignant phenotype of tumor cells using the methods and compositions of the present invention in combination therapy, one contacts a “target” cell with the compositions described herein and at least one other agent. These compositions are provided in a combined amount effective to kill or inhibit proliferation of the cell. This process may involve contacting the cells with the immunotherapeutic agent and the agent(s) or factor(s) at the same time. This may be achieved by contacting the cell with a single composition or pharmacological formulation that includes both agents, or by contacting the cell with two distinct compositions or formulations, at the same time.

Alternatively, immunotherapy with the fusion proteins described herein precedes or follows the other agent treatment by intervals ranging from minutes to weeks. In embodiments where the other agent and immunotherapy are applied separately to the cell, one would generally ensure that a significant period of time did not expire between the time of each delivery, such that the fusion protein and chemotherapeutic agent would still be able to exert an advantageously combined effect on the cell. In such instances, it is contemplated that cells are contacted with both modalities within about 12-24 hours of each other and, more preferably, within about 6-12 hours of each other, with a delay time of only about 12 hours being most preferred. In some situations, it may be desirable to extend the time period for treatment significantly, however, where several days (2 to 7) to several weeks (1 to 8) lapse between the respective administrations.

In some embodiments, more than one administration of the immunotherapeutic composition of the present invention or the other agent is utilized. Various combinations may be employed, where the fusion protein is “A” and the other agent is “B”, as exemplified below:

A/B/A, B/A/B, B/B/A, A/A/B, B/A/A, A/B/B, B/B/B/A, B/B/A/B, A/A/B/B, A/B/A/B, A/B/B/A, B/B/A/A, B/A/B/A, B/A/A/B, B/B/B/A, A/A/A/B, B/A/A/A, A/B/A/A, A/A/B/A, A/B/B/B, B/A/B/B, B/B/A/B.

Other combinations are contemplated. Again, to achieve cell killing, both agents are delivered to a cell in a combined amount effective to kill or disable the cell.

In some embodiments of the invention, one or more compounds of the invention and an additional active agent are administered to a subject, more typically a human, in a sequence and within a time interval such that the compound can act together with the other agent to provide an enhanced benefit relative to the benefits obtained if they were administered otherwise. For example, the additional active agents can be co-administered by co-formulation, administered at the same time or administered sequentially in any order at different points in time; however, if not administered at the same time, they should be administered sufficiently close in time so as to provide the desired therapeutic or prophylactic effect. In some embodiments, the compound and the additional active agents exert their effects at times which overlap. Each additional active agent can be administered separately, in any appropriate form and by any suitable route. In other embodiments, the compound is administered before, concurrently or after administration of the additional active agents.

In various examples, the compound and the additional active agents are administered less than about 1 hour apart, at about 1 hour apart, at about 1 hour to about 2 hours apart, at about 2 hours to about 3 hours apart, at about 3 hours to about 4 hours apart, at about 4 hours to about 5 hours apart, at about 5 hours to about 6 hours apart, at about 6 hours to about 7 hours apart, at about 7 hours to about 8 hours apart, at about 8 hours to about 9 hours apart, at about 9 hours to about 10 hours apart, at about 10 hours to about 11 hours apart, at about 11 hours to about 12 hours apart, no more than 24 hours apart or no more than 48 hours apart. In other examples, the compound and the additional active agents are administered concurrently. In yet other examples, the compound and the additional active agents are administered concurrently by co-formulation.

In other examples, the compound and the additional active agents are administered at about 2 to 4 days apart, at about 4 to 6 days apart, at about 1 week part, at about 1 to 2 weeks apart, or more than 2 weeks apart.

In certain examples, the inventive compound and optionally the additional active agents are cyclically administered to a subject. Cycling therapy involves the administration of a first agent for a period of time, followed by the administration of a second agent and/or third agent for a period of time and repeating this sequential administration. Cycling therapy can provide a variety of benefits, e.g., reduce the development of resistance to one or more of the therapies, avoid or reduce the side effects of one or more of the therapies, and/or improve the efficacy of the treatment.

In other examples, one or more compound of some embodiments of the present invention and optionally the additional active agent are administered in a cycle of less than about 3 weeks, about once every two weeks, about once every 10 days or about once every week. One cycle can comprise the administration of an inventive compound and optionally the second active agent by infusion over about 90 minutes every cycle, about 1 hour every cycle, about 45 minutes every cycle, about 30 minutes every cycle or about 15 minutes every cycle. Each cycle can comprise at least 1 week of rest, at least 2 weeks of rest, at least 3 weeks of rest. The number of cycles administered is from about 1 to about 12 cycles, more typically from about 2 to about 10 cycles, and more typically from about 2 to about 8 cycles.

Courses of treatment can be administered concurrently to a subject, i.e., individual doses of the additional active agents are administered separately yet within a time interval such that the inventive compound can work together with the additional active agents. For example, one component can be administered once per week in combination with the other components that can be administered once every two weeks or once every three weeks. In other words, the dosing regimens are carried out concurrently even if the therapeutics are not administered simultaneously or during the same day.

The additional active agents can act additively or, more typically, synergistically with the inventive compound(s). In one example, one or more inventive compound is administered concurrently with one or more second active agents in the same pharmaceutical composition. In another example, one or more inventive compound is administered concurrently with one or more second active agents in separate pharmaceutical compositions. In still another example, one or more inventive compound is administered prior to or subsequent to administration of a second active agent. The invention contemplates administration of an inventive compound and a second active agent by the same or different routes of administration, e.g., oral and parenteral. In certain embodiments, when the inventive compound is administered concurrently with a second active agent that potentially produces adverse side effects including, but not limited to, toxicity, the second active agent can advantageously be administered at a dose that falls below the threshold that the adverse side effect is elicited.

Other factors that may be used in combination therapy include, but are not limited to, factors that cause DNA damage such as γ-rays, X-rays, and/or the directed delivery of radioisotopes to tumor cells. Other forms of DNA damaging factors are also contemplated such as microwaves and UV-irradiation. Dosage ranges for X-rays range from daily doses of 50 to 200 roentgens for prolonged periods of time (3 to 4 weeks), to single doses of 2000 to 6000 roentgens. Dosage ranges for radioisotopes vary widely, and depend on the half-life of the isotope, the strength and type of radiation emitted, and the uptake by the neoplastic cells. The skilled artisan is directed to “Remington's Pharmaceutical Sciences” 15th Edition, chapter 33, in particular pages 624-652. Some variation in dosage will necessarily occur depending on the condition of the subject being treated. The person responsible for administration will, in any event, determine the appropriate dose for the individual subject. Moreover, for human administration, preparations should meet sterility, pyrogenicity, general safety and purity standards as required by FDA Office of Biologics standards.

In some embodiments of the present invention, the regional delivery fusion proteins to patients with cancers is utilized to maximize the therapeutic effectiveness of the delivered agent. Similarly, the chemo- or radiotherapy may be directed to a particular, affected region of the subject's body. Alternatively, systemic delivery of the immunotherapeutic composition and/or the agent may be appropriate in certain circumstances, for example, where extensive metastasis has occurred.

In addition to combining the fusion proteins of some embodiments of the present invention with chemo- and radiotherapies, it also is contemplated that traditional gene therapies are used. For example, targeting of p53 or p16 mutations along with treatment with the fusion proteins of the present invention provides an improved anti-cancer treatment. The present invention contemplates the co-treatment with other tumor-related genes including, but not limited to, p21, Rb, APC, DCC, NF-I, NF-2, BCRA2, p16, FHIT, WT-I, MEN-I, MEN-II, BRCA1, VHL, FCC, MCC, ras, myc, neu, raf erb, src, fms, jun, trk, ret, gsp, hst, bcl, and abl.

An attractive feature of the present invention is that the therapeutic compositions may be delivered to local sites in a patient by a medical device. Medical devices that are suitable for use in the present invention include known devices for the localized delivery of therapeutic agents. Such devices include, but are not limited to, catheters such as injection catheters, balloon catheters, double balloon catheters, microporous balloon catheters, channel balloon catheters, infusion catheters, perfusion catheters, etc., which are, for example, coated with the therapeutic agents or through which the agents are administered; needle injection devices such as hypodermic needles and needle injection catheters; needleless injection devices such as jet injectors; coated stents, bifurcated stents, vascular grafts, stent grafts, etc.; and coated vaso-occlusive devices such as wire coils.

Exemplary devices are described in U.S. Pat. Nos. 5,935,114; 5,908,413; 5,792,105; 5,693,014; 5,674,192; 5,876,445; 5,913,894; 5,868,719; 5,851,228; 5,843,089; 5,800,519; 5,800,508; 5,800,391; 5,354,308; 5,755,722; 5,733,303; 5,866,561; 5,857,998; 5,843,003; and 5,933,145; the entire contents of which are incorporated herein by reference. Exemplary stents that are commercially available and may be used in the present application include the RADIUS (SCIMED LIFE SYSTEMS, Inc.), the SYMPHONY (Boston Scientific Corporation), the Wallstent (Schneider Inc.), the PRECEDENT II (Boston Scientific Corporation) and the NIR (Medinol Inc.). Such devices are delivered to and/or implanted at target locations within the body by known techniques.

In some embodiments, composition embodiments of the present invention are co-administered with an anti-cancer agent (e.g., chemotherapeutic). In some embodiments, method embodiments of the present invention encompass co-administration of an anti-cancer agent (e.g., chemotherapeutic). The present invention is not limited by type of anti-cancer agent co-administered. Indeed, a variety of anti-cancer agents are contemplated to be useful in the present invention including, but not limited to, Acivicin; Aclarubicin; Acodazole Hydrochloride; Acronine; Adozelesin; Adriamycin; Aldesleukin; Alitretinoin; Allopurinol Sodium; Altretamine; Ambomycin; Ametantrone Acetate; Aminoglutethimide; Amsacrine; Anastrozole; Annonaceous Acetogenins; Anthramycin; Asimicin; Asparaginase; Asperlin; Azacitidine; Azetepa; Azotomycin; Batimastat; Benzodepa; Bexarotene; Bicalutamide; Bisantrene Hydrochloride; Bisnafide Dimesylate; Bizelesin; Bleomycin Sulfate; Brequinar Sodium; Bropirimine; Bullatacin; Busulfan; Cabergoline; Cactinomycin; Calusterone; Caracemide; Carbetimer; Carboplatin; Carmustine; Carubicin Hydrochloride; Carzelesin; Cedefingol; Celecoxib; Chlorambucil; Cirolemycin; Cisplatin; Cladribine; Crisnatol Mesylate; Cyclophosphamide; Cytarabine; Dacarbazine; DACA (N42-(Dimethyl-amino)ethyllacridine-4-carboxamide); Dactinomycin; Daunorubicin Hydrochloride; Daunomycin; Decitabine; Denileukin Diftitox; Dexormaplatin; Dezaguanine; Dezaguanine Mesylate; Diaziquone; Docetaxel; Doxorubicin; Doxorubicin Hydrochloride; Droloxifene; Droloxifene Citrate; Dromostanolone Propionate; Duazomycin; Edatrexate; Eflornithine Hydrochloride; Elsamitrucin; Enloplatin; Enpromate; Epipropidine; Epirubicin Hydrochloride; Erbulozole; Esorubicin Hydrochloride; Estramustine; Estramustine Phosphate Sodium; Etanidazole; Ethiodized Oil I 131; Etoposide; Etoposide Phosphate; Etoprine; Fadrozole Hydrochloride; Fazarabine; Fenretinide; Floxuridine; Fludarabine Phosphate; Fluorouracil; 5-FdUMP; Flurocitabine; Fosquidone; Fostriecin Sodium; FK-317; FK-973; FR-66979; FR-900482; Gemcitabine; Geimcitabine Hydrochloride; Gemtuzumab Ozogamicin; Gold Au 198; Goserelin Acetate; Guanacone; Hydroxyurea; Idarubicin Hydrochloride; Ifosfamide; Ilmofosine; Interferon Alfa-2a; Interferon Alfa-2b; Interferon Alfa-n1; Interferon Alfa-n3; Interferon Beta-la; Interferon Gamma-1b; Iproplatin; Irinotecan Hydrochloride; Lanreotide Acetate; Letrozole; Leuprolide Acetate; Liarozole Hydrochloride; Lometrexol Sodium; Lomustine; Losoxantrone Hydrochloride; Masoprocol; Maytansine; Mechlorethamine Hydrochloride; Megestrol Acetate; Melengestrol Acetate; Melphalan; Menogaril; Mercaptopurine; Methotrexate; Methotrexate Sodium; Methoxsalen; Metoprine; Meturedepa; Mitindomide; Mitocarcin; Mitocromin; Mitogillin; Mitomalcin; Mitomycin; Mytomycin C; Mitosper; Mitotane; Mitoxantrone Hydrochloride; Mycophenolic Acid; Nocodazole; Nogalamycin; Oprelvekin; Ormaplatin; Oxisuran; Paclitaxel; Pamidronate Disodium; Pegaspargase; Peliomycin; Pentamustine; Peplomycin Sulfate; Perfosfamide; Pipobroman; Piposulfan; Piroxantrone Hydrochloride; Plicamycin; Plomestane; Porfimer Sodium; Porfiromycin; Prednimustine; Procarbazine Hydrochloride; Puromycin; Puromycin Hydrochloride; Pyrazofurin; Riboprine; Rituximab; Rogletimide; Rolliniastatin; Safingol; Safingol Hydrochloride; Samarium/Lexidronam; Semustine; Simtrazene; Sparfosate Sodium; Sparsomycin; Spirogermanium Hydrochloride; Spiromustine; Spiroplatin; Squamocin;

Squamotacin; Streptonigrin; Streptozocin; Strontium Chloride Sr 89; Sulofenur; Talisomycin; Taxane; Taxoid; Tecogalan Sodium; Tegafur; Teloxantrone Hydrochloride; Temoporfin; Teniposide; Teroxirone; Testolactone; Thiamiprine; Thioguanine; Thiotepa; Thymitaq; Tiazofurin; Tirapazamine; Tomudex; TOP-53; Topotecan Hydrochloride; Toremifene Citrate; Trastuzumab; Trestolone Acetate; Triciribine Phosphate; Trimetrexate; Trimetrexate Glucuronate; Triptorelin; Tubulozole Hydrochloride; Uracil Mustard; Uredepa; Valrubicin; Vapreotide; Verteporfin; Vinblastine; Vinblastine Sulfate; Vincristine; Vincristine Sulfate; Vindesine; Vindesine Sulfate; Vinepidine Sulfate; Vinglycinate Sulfate; Vinleurosine Sulfate; Vinorelbine Tartrate; Vinrosidine Sulfate; Vinzolidine Sulfate; Vorozole; Zeniplatin; Zinostatin; Zorubicin Hydrochloride; 2-Chlorodeoxyadenosine; 2′-Deoxyformycin; 9-aminocamptothecin; raltitrexed; N-propargyl-5,8-dideazafolic acid; 2-chloro-2′-arabino-fluoro-2′-deoxyadenosine; 2-chloro-2′-deoxyadenosine; anisomycin; trichostatin A; hPRL-G129R; CEP-751; linomide; sulfur mustard; nitrogen mustard (mechlorethamine); cyclophosphamide; melphalan; chlorambucil; ifosfamide; busulfan; N-methyl-N-nitrosourea (MNU); N, N′-Bis(2-chloroethyl)-N-nitrosourea (BCNU); N-(2-chloroethyl)-N′-cyclohex-yl-N-nitrosourea (CCNU); N-(2-chloroethyl)-N′-(trans-4-methylcyclohexyl-N-nitrosourea (MeCCNU); N-(2-chloroethyl)-N′-(diethyl)ethylphosphonate-N-nit-rosourea (fotemustine); streptozotocin; diacarbazine (DTIC); mitozolomide; temozolomide; thiotepa; mitomycin C; AZQ; adozelesin; Cisplatin; Carboplatin; Ormaplatin; Oxaliplatin; C1-973; DWA 2114R; JM216; JM335; Bis (platinum); tomudex; azacitidine; cytarabine; gemcitabine; 6-Mercaptopurine; 6-Thioguanine; Hypoxanthine; teniposide; 9-amino camptothecin; Topotecan; CPT-11; Doxorubicin; Daunomycin; Epirubicin; darubicin; mitoxantrone; losoxantrone; Dactinomycin (Actinomycin D); amsacrine; pyrazoloacridine; all-trans retinol; 14-hydroxy-retro-retinol; all-trans retinoic acid; N-(4-Hydroxyphenyl) retinamide; 13-cis retinoic acid; 3-Methyl TTNEB; 9-cis retinoic acid; fludarabine (2-F-ara-AMP); and 2-chlorodeoxyadenosine (2-Cda).

Other anti-cancer agents include: Antiproliferative agents (e.g., Piritrexim Isothionate), Antiprostatic hypertrophy agent (e.g., Sitogluside), Benign prostatic hypertrophy therapy agents (e.g., Tamsulosin Hydrochloride), Prostate growth inhibitor agents (e.g., Pentomone), and Radioactive agents: Fibrinogen 1 125; Fludeoxyglucose F 18; Fluorodopa F 18; Insulin I 125; Insulin I 131; Iobenguane I 123; Iodipamide Sodium I 131; Iodoantipyrine I 131; Iodocholesterol I 131; Iodohippurate Sodium I 123; Iodohippurate Sodium I 125; Iodohippurate Sodium I 131; Iodopyracet I 125; Iodopyracet I 131; Iofetamine Hydrochloride I 123; Iomethin I 125; Iomethin I 131; Iothalamate Sodium I 125; Iothalamate Sodium I 131; Iotyrosine I 131; Liothyronine I 125; Liothyronine I 131; Merisoprol Acetate Hg 197; Merisoprol Acetate Hg 203; Merisoprol Hg 197; Selenomethionine Se 75; Technetium Tc 99m Antimony Trisulfide Colloid; Technetium Tc 99m Bicisate; Technetium Tc 99m Disofenin; Technetium Tc 99m Etidronate; Technetium Tc 99m Exametazime; Technetium Tc 99m Furifosmin; Technetium Tc 99m Gluceptate; Technetium Tc 99m Lidofenin; Technetium Tc 99m Mebrofenin; Technetium Tc 99m Medronate; Technetium Tc 99m Medronate Disodium; Technetium Tc 99m Mertiatide; Technetium Tc 99m Oxidronate; Technetium Tc 99m Pentetate; Technetium Tc 99m Pentetate Calcium Trisodium; Technetium Tc 99m Sestamibi; Technetium Tc 99m Siboroxime; Technetium Tc 99m Succimer; Technetium Tc 99m Sulfur Colloid; Technetium Tc 99m Teboroxime; Technetium Tc 99m Tetrofosmin; Technetium Tc 99m Tiatide; Thyroxine I 125; Thyroxine I 131; Tolpovidone I 131; Triolein I 125; Triolein I 131.

Another category of anti-cancer agents is anti-cancer Supplementary Potentiating Agents, including: Tricyclic anti-depressant drugs (e.g., imipramine, desipramine, amitryptyline, clomipramine, trimipramine, doxepin, nortriptyline, protriptyline, amoxapine and maprotiline); non-tricyclic anti-depressant drugs (e.g., sertraline, trazodone and citalopram); Ca++ antagonists (e.g., verapamil, nifedipine, nitrendipine and caroverine); Calmodulin inhibitors (e.g., prenylamine, trifluoroperazine and clomipramine); Amphotericin B; Triparanol analogues (e.g., tamoxifen); antiarrhythmic drugs (e.g., quinidine); antihypertensive drugs (e.g., reserpine); Thiol depleters (e.g., buthionine and sulfoximine) and Multiple Drug Resistance reducing agents such as Cremaphor EL.

Still other anticancer agents are those selected from the group consisting of: annonaceous acetogenins; asimicin; rolliniastatin; guanacone, squamocin, bullatacin; squamotacin; taxanes; paclitaxel; gemcitabine; methotrexate FR-900482; FK-973; FR-66979; FK-317; 5-FU; FUDR; FdUMP; Hydroxyurea; Docetaxel; discodermolide; epothilones; vincristine; vinblastine; vinorelbine; meta-pac; irinotecan; SN-38; 10-OH campto; topotecan; etoposide; adriamycin; flavopiridol; Cis-Pt; carbo-Pt; bleomycin; mitomycin C; mithramycin; capecitabine; cytarabine; 2-C1-2′deoxyadenosine; Fludarabine-PO4; mitoxantrone; mitozolomide; Pentostatin; and Tomudex.

Other cancer therapies include hormonal manipulation. In some embodiments, the anti-cancer agent is tamoxifen or the aromatase inhibitor arimidex (i.e., anastrozole).

In some embodiments, the additional agent is Mitomycin C.

In some embodiments, the therapies described herein are used in combination with other immunotherapies (e.g., CAR-T/TCR and/or checkpoint inhbitors).

EXPERIMENTAL

The following examples are provided in order to demonstrate and further illustrate certain preferred embodiments and aspects of the present invention and are not to be construed as limiting the scope thereof.

Example 1—Generation of Nanobodies and Constructs

Reagents, mice and cell lines. Recombinant human IL-15 (rIL-15), human IL-2 (rhIL-2), murine IL-4 (rmIL-4) and murine interferon gamma (rmIFNg) were purchased from Peprotech Inc (Rocky Hill, N.J.). The IL-2-dependent CTLL-2 cell line (American Type Culture Collection, ATCC) was maintained in RPMI1640 medium containing 10% FCS, 2 mM glutamine, 10 ng/ml rhIL-2.

C57B16 mice were obtained from Taconic (Taconic Farms, Rye, Denmark) and bred in-house in a Specific-pathogen-free (SPF) facility. Tumor challenge was performed by s.c. injection with 2×105 B16 melanoma cells (ATCC).

The CHO cell line (ATCC) was used to generate cells expressing the murine or human mannose receptor (MRC1; CD206). STable transfectants were generated by electorporating the cells with a pCDNA3.1 plasmid containing the relevant cDNA (synthesized by Genscript). MRC1-expressing cells were selected by flow sorting of cells staining positive using an anti-MRC1 antibody.

NS0 hybridoma scells (Sigma Aldrich) were used to generate human/mouse FOLR2-expressing cells. Cells were transduced with pMSCV IRES GFP vectors expressing cDNA-containing encoding the relevant receptor (obtained from OriGene). Stably transduced cells were selected by flow sorting of GFP+ cells staining positive with an anti-FOLR2 mAb. All cells were maintained in RPMI1640 medium containing 10% FCS.

The Escherichia coli production strain Rv308 was obtained from ATCC.

Generation of Anti-MRC1 sdAbs. For the generation of a phage display library with human/mouse cross-reactivity, a llama (Llama glama) was immunized s.c. with alternating doses of human and mouse recombinant MRC1 (R&D Systems) in GERBU adjuvant with 7-day intervals for a total of 6 weeks. The two initial immunizations utilized 200 μg MRC1, whereas subsequent doses were 100 μg each. Upon completion of the immunization schedule, total RNA was isolated from peripheral blood lymphocytes. Construction of a VHH library and subsequent biopanning and next-generation sequencing was performed by a commercial service provider (Creative Biolabs, Shirley, N.Y.). In brief, cDNA was generated using a AMV Super Reverse Transcriptase kit (HT Biotechnology Ltd, Cambridge, UK) according to the manufacturer's instructions, using Oligo(dT) primers. Amplified VHH sequences were inserted into the pCDisplay-3M phagemid vector (Creative Biolabs), and electroporated into E. coli TG1 cells. Transformants were infected with M13K01 helper phages (New England Biolabs) to generate VHH-expressing phages. Phage biopanning was performed using recombinant human and mouse MRC1 (R&D systems). After 4 successive rounds of panning, DNA from the enriched phage library was subjected to next generation sequencing to score enriched clones using the VectorNTI bioinformatics software package (Thermo Scientific). The most highly enriched sequences were those represented by SEQ ID NOs:30-56. Top candidates were codon-optimized for expression in E. coli (amino acid and nucleic acid sequences provided as SEQ ID NOs:57-108), and synthesized fragments inserted downstream of the PelB signal of the pHOG21 expression vector. Monovalent sdAb candidates containing an N-terminal cMyc/6×His tag were expressed and purified as specified below, and binding to MRC1-expressing CHO cells verified by flow cytometry staining using a PE-conjugated anti-His antibody.

Generation of Anti-FOLR2 sdAbs. Immunization of llamas was performed as described for the anti-MRC1 antibodies, using recombinant human and mouse FOLR2 (R&D systems). Upon completion of the immunization schedule, total RNA was isolated from peripheral blood lymphocytes and cDNA synthesized using the First Stand cDNA synthesis kit (Thermo Scientific), utilizing oligo(dT) primers, according to the supplied protocol. VHH sequences were amplified in a two-step approach, based on a previously published protocol. In short, V_(H)Hs were amplified using primers CALL001 (5′-GTCCTGGCTGCTCTTCTACAAGG-3; SEQ ID NO:148) and CALL002 (5′-GGTACGTGCTGTTGAACTGTTCC-3; SEQ ID NO:149′), specific for the V_(H)H leader sequence and CH2 exon, respectively. The PCR mixture was separated on 1% agarose gels, and the 700 bp VHH fragments were extracted and subjected to a second PCR using nested primers VHH-Back (5′-GATGTGCAGCTGCAGGAGTCTGGRGGAGG-3′; SEQ ID NO:150; PstI cut site underlined) and VHH-For: (5′-CTAGTGCGGCCGCTGGAGACGGTGACCTGGGT-3′; SEQ ID NO:151; Eco91I site underlined), specific for framework 1 and framework 4 regions, respectively. PCR fragments were cut using PstI/Eco91I restriction enzymes, and ligated into the corresponding sites of the pMESY4 phagemid vector. Ligated vector was electroporated into E. Coli SS320 cells and plated on LB plates containing 100 ug/mL ampicillin. Cells were collected by scraping, and stored at −80° C. in LB medium with 50% glycerol. For production of phages, cells were infected with VSCM13 helper phages (Cat.no. 200251; Stratagene). FOLR2-specific phages were enriched by three consecutive rounds of cell-based in vitro selection. Negative selection was done using a combination of molecular and cell-based banning. For cell-based panning, phages were incubated with 50×106 NS0 cells for negative selection, with subsequent positive selection and elution of bound particles from NS0 cells expressing human or mouse FOLR2. Individual clones were screened by flow cytometry for selective binding to tumor cells overexpressing FOLR2. VHH sequences from binders were codon optimized for expression in E. coli, and expressed alone or in fusion with cytokine partners as specified below.

Generation of Anti-LGMN sdAbs. Immunization of llamas and subsequent library construction is performed as described for FOLR2, using recombinant human and murine legumain extracellular domains as immunogens, with identical immunization dosage/intervals. A sdAb library is constructed by cDNA synthesis using RNA extracted from PBMCs collected at the termination of the immunization protocol. The library is generated in the pMESY4 phagemid vector.

Generation of sdAb/cytokine fusion proteins. Nucleotide sequences encoding fusion proteins were codon-optimized for expression in E. coli and generated by gene synthesis for insertion into the NcoI/NotI site of the pHOG21 expression vector, downstream of the PelB leader sequence. A cMyc/6×His tag 3′ of the MCS site was utilized to generate tagged variants of the fusion proteins. The relevant sdAb or scFv fragments were fused to cytokine moieties using the llama IgG2 hinge (AHHSEDPSSKAPKAPMA; SEQ ID NO: 109) or a (G₄S)₃ flexible linker (GGGGSGGGGSGGGGS; SEQ ID NO:110). The choice of linker did not seem to influence protein yield or biological activity of the fusion protein.

Expression and Purification of proteins in E. coli. E. coli (RV308) cells (ATCC) were transformed with the pHOG21 plasmids described above and individual colonies from a freshly streaked agar plate were grown in LB media containing 100 μg/mL ampicillin and 100 mM glucose at 37° C. for 7h. Preculture innoculum was transferred to 100 mL minimal medium and culture ON at 30° C. ON cultures were used to innoculate a bioreactor containing 4L minimal medium. Fermentation was performed at 20-30° C. using 02-stat control, and feeding with glucose was initiated upon completion of the batch phase, signified by a rapid increase in dissolved 02 levels. Protein production was induced by injection of IPTG to a final concentration of 1 mM, and bacteria harvested by centrifugation at 50000×g 6h after induction. For extraction of the periplasmic fraction, bacterial pellets were dissolved in periplasmic extraction buffer, stirred at room temperature for 10 min and pelleted by centrifugation at 14 000×g. Pellets were dissolved in cold distilled water, incubated at 4° C. for 10 minutes and centrifuged at 17 000×g for 30 minutes. Supernatant was filtered, and imidazol (final conc. 30 mM) and NaCl (final conc. 500 mM).

All proteins were purified using immobilized metal affinity chromatography (IMAC) using HiTrap IMAC HP columns (GE Healthcare), followed by cation exchange chromatography (CEX) on pre-packed HiTrap Capto SP ImpRes columns (GE Healthcare) to remove endotoxin. Endotoxin levels were determined using a LAL Chromogenic Endotoxin Quantitation Kit (Thermo Scientific). For proteins utilized in functional assays, a final polishing step was performed by size exclusion chromatography (SEC) using Superdex 75 10/300 GL columns (GE Healthcare) in endotoxin-free phosphate buffered saline pH 7.4 (PBS).

Proteins were transferred onto an Immobilon P membrane (Millipore Corporation, Bedford, USA) for immunoblotting. After blocking the membrane with phosphate buffered saline containing 0.2% Tween20 (PBS-Tween) and 1% skimmed milk, the relevant primary antibody was added and incubated for 2 hours at room temperature. Following washing, a HRP-labeled secondary antibody was added, followed by 1 hour incubation. The membrane was washed several times with PBS-Tween buffer before visualization of peroxidase activity by addition of SuperSignal West Pico Chemiluminescent Substrate (Thermo Scientific).

In vitro T cell proliferation assays. To assess the biological effect of sdAb IL2/IL15 fusion proteins in vitro, we utilized the IL2-dependent T cell hybridoma CTLL-2 (ATCC). CTLL-2 cells were maintained in RPMI1640 medium with rhIL-2. Prior to use, cells were washed and starved by 24h incubation in RPMI medium without rhIL-2. Candidate fusion proteins were added to the cells in 96-well plates, and incubated for 48h, with addition of 3H-thymidine for the last 18h of culture. Cells were harvested and measured using a TopCount scintillation counter (PerkinElmer, Waltham, Mass.).

Cells were harvested on nitrocellulose paper, and counts per minute (cpm) determined using a scintillation counter (PerkinElmer). rhIL-2 or rhIL-15 was used to generate a reference for growth-promoting activity.

Flow Cytometry

Binding of sdAb/cytokine fusion proteins was assayed by flow cytometry by exposing cells to the relevant fusion protein, followed by staining with antibodies reactive against the cytokine moiety or the 6×His tag.

Expression and functional evaluation of 206Nb-RLI fusion protein. To evaluate the possibility of generating sdAb/cytokine fusion proteins, we utilized codon-optimized construct encompassing the scFv fragment of a previously characterized MRC1-specific sdAb described in US patent application US20120301394 (clone 1; hereafter referred to as 206Nb). The 206Nb fragment (SEQ ID NOs: 111 and 112) was linked via a Llama IgG2 hinge (SEQ ID NO: 112 and 113) to a sequence encoding the IL15 receptor sushi/hIL15 fusion protein (IL15RLI; SEQ ID 6, 7). The resulting construct, referred to as 206Nb-RLI (SEQ ID NO: 1 and 2), was inserted downstream of the PelB signal sequence (MKSLLPTAAAGLLLLAAQPA; SEQ ID NO:152) of the pHOG21 expression vector, and the construct electroporated into RV380 cells.

Following IPTG-induced periplasmic expression at 30° C., the protein was isolated by affinity chromatography using sepharose-conjugated anti-IL15 column, followed by CEX. The resulting protein was present as a monomer of expected size of approx. 40 kDa, and was detected in a western blot using an anti-IL15 mAb (#MAB2471; R&D systems) (FIG. 4, lane 2). Binding to mMRC1-expressing CHO cells (CHO-MR) was verified by flow cytometry, using an APC-conjugated anti-IL15 antibody (#IC2471A; R&D Systems) for detection (FIG. 5). Functionality of the IL15RLI unit was confirmed by a CTLL-2 proliferation assay (FIG. 6).

A version of the fusion protein containing a C-terminal cMyc/6×His tag was also produced, and isolated by IMAC/CEX. Western blot using an anti-cMyc mAb (9E10; Abcam) confirmed a single band of the expected size (data not shown). CTLL-2 assays confirmed proliferative capability comparable to that of the tag-free variant (data not shown).

Expression and functional evaluation of 206Nb-hIL15 fusion protein. 206Nb was fused to a sequence encoding human IL15 (SEQ ID NO:116 and 117), linked by a llama IgG2 hinge (SEQ ID NO:109), and a C-terminal cMyc/6×His tag. The sequence for the 206Nb-hIL15 fusion protein is provided as SEQ ID NO:138. Production was performed as described for 206RLI. Following IMAC/CEX purification, a single band of the expected size (approx. 30 kDa), detectable in western blots using an anti-IL15 mAb (data not shown) was observed. The proliferation-inducing function of the fusion protein was superior to that of rhIL15 when used in CTLL-2 assays (FIG. 7). Flow cytometry confirmed binding to CHO cells expressing mMRC1, with detection using antibodies against IL15 or the 6×His tag.

Expression and functional evaluation of a 206Nb-hIL2 fusion protein. 206Nb was fused to a sequence encoding human IL2 (SEQ ID NOs.: 118 and 119), linked by a llama IgG2 hinge (SEQ ID NO:109), and a C-terminal cMyc/6xHis tag. Production was performed as described above. Following IMAC/CEX purification, a single band of the expected size (approx. 33 kDa), detectable in western blots using an anti-2 mAb (FIG. 8, lane 3) was observed. The protein showed strong proliferation-inducing effects, exceeding that of rhI12 in CTLL-2 assays (FIG. 9). Flow cytometry confirmed binding to CHO cells expressing mMRC1, with detection using antibodies against IL2 or the 6×His tag.

Expression and functional evaluation of a CL10scFv-IL15RLI fusion protein. We next wanted to explore the potential for extending macrophage targeting to fusion proteins containing scFv targeting units. A codon-optimized construct encompassing the scFv fragment of the rat anti-mouse FOLR2 mAb CL10 (SEQ ID NO:120 and 121; obtained from US patent application US20140010756), with VH and VL fragments connected by a (G₄S)₃ linker, was fused to IL15RLI (SEQ ID NO: 114 and 115), containing a C-terminal cMyc/6×His tag, via a (G₄S)₃ linker and inserted into the pHOG vector downstream of the PelB signal peptide. Protein expression was induced by ON induction with 1 mM IPTG at 25° C., and purification was done by IMAC/CEX. The purified protein (size approx 55 kDa; FIG. 10, lanes 6-7) showed binding to mFOLR2-expressing NS0 cells by flow cytometry, detected using an anti-IL15 or anti-6×His antibody (FIG. 11). Functionality of the IL15RLI unit was verified by a CTLL-2 assay.

206Nb-RLI binding to in vitro M2-polarized macrophages. To determine the ability of the 206Nb-RLI protein to bind to macrophages of different polarization, we cultured d+7 BMDMs for 24h in the presence of rmIL-4 (long/mL) or rmIFNg (100 ng/mL), known to induce an M2 or M1 phenotype, respectively. Flow cytometry staining using the 206Nb-RLI protein resulted in a preferential staining of IL-4-treated, M2-like macrophages (FIG. 12).

Expression and functional evaluation of a FOLR2sdAb-RLI fusion protein. Biopanning of the FOLR2 sdAb library lead to the identification of a highly enriched clone (SEQ ID NO:122) that was codon-optimized (SEQ ID NO:123), and fused via a (G₄S)₃ linker to IL15RLI (SEQ ID NO: 114 and 115). The sequence of the entire construct is provided as SEQ ID NO:141. The protein was expressed in pHOG21 with a C-terminal cMyc/6×His tag.

In vitro binding of FOLR2sdAb-RLI to tumor-associated macrophages. To evaluate binding of the FOLR2sdAb-RLI protein to physiologically differentiated tumor macrophages, we performed flow cytometry analyses of single-cell suspensions prepared from established B16 tumors. The tumor-resident CD11b+ population was found to consist primarily of Ly6GHiLy6Clo cells, showing preferential binding of FOLR2-RLI compared to the Ly6GNegLy6CNeg fraction and CD11bNeg cells (FIG. 13), consistent with reactivity of the fusion protein against tumor-associated macrophages.

Example 2—Animal Experiments

Well-established, clinically relevant murine models of various malignancies are used to evaluate the treatment efficacy of 206RLI. We have selected a screening panel of cancer types that are known to have a high degree of macrophage infiltration, and which represents patient groups with limited current therapeutic options. This includes lung cancer, breast cancer, pancreatic cancer, prostate cancer, melanoma and multiple myeloma. The cell lines utilized are commonly used and well-characterized, produce tumors with consistent growth kinetics, and are used to model advanced-stage, metastatic disease.

Therapy evaluation is performed using both subcutaneous and disseminated tumors. For melanoma and multiple myeloma, we have previously assessed the outcome of treatment with current standard-of-care regimens, and of monotherapy with checkpoint inhibitors including anti-PDL1 and anti-CTLA4. This will greatly facilitate evaluation of 206RLI as an adjunct to other treatment regimens. Initiation of treatment is delayed until the development of large lesions to allow evaluation of efficacy in advanced-stage disease. Intravenous administration of tumor cells allows studies of metastatic disease, and experiments are extended to this. Extension to orthotopic and spontaneous models of other types of malignancies are also performed.

Protein Production and Isolation:

Several candidate constructs have been constructed by gene synthesis and tested in functional assays (see below), and the best performing candidate (schematically illustrated in FIG. 1A) has been chosen for further development. Negative controls in the form of proteins containing a) an irrelevant targeting unit and/or b) a non-functional IL15 unit have also been developed.

By optimizing vectors used for periplasmic protein expression in E. Coli, we have generated plasmid constructs that allow high-yield production of soluble, tag-free protein in conventional shaker flask as well as in high-density cultures. Further purification is achieved using an anti-IL15 antibody immunoaffinity column.

In Vitro Characterization:

Isolated 206RLI protein has been verified to bind to human and murine CD206 with high affinity, confirming that the recombinant fusion protein retains target-binding properties. Functionality of the IL15 unit has been verified in T cell proliferation assays, showing potent growth-promoting effects on both murine and human T cells exceeding that of purified native IL15 (FIG. 2).

In Vivo Therapeutic Experiments:

The therapeutic efficacy of the 206RLI protein has been evaluated in preliminary experiments in murine models of myeloma and melanoma.

Experiments were performed in mice harboring palpable subcutaneous tumors with a diameter of >10 mm, which constitutes a high tumor burden. Treatment was done by systemic (i.p.) administration of 100n/dose every second day for nine days. In both cases, 206RLI treatment leads to the formation of a central necrotic ulceration within the tumors within a few days, and a rapid and dramatic shrinkage of tumors (FIG. 3A).

By day+10, the tumor bed was reduced to a dense scar tissue in the majority of the mice (FIG. 3B). In accordance with these observation, histochemical examination of the tumor site on day+10 after initiation of treatment revealed the formation of massive inflammatory infiltrates within the tumor bed after treatment, with tumor cells limited to small, encapsulated areas.

All publications, patents, patent applications and accession numbers mentioned in the above specification are herein incorporated by reference in their entirety. Although the invention has been described in connection with specific embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications and variations of the described compositions and methods of the invention will be apparent to those of ordinary skill in the art and are intended to be within the scope of the following claims. 

We claim:
 1. A fusion protein for targeting of tumor-associated macrophages comprising: i) a targeting unit that specifically binds to a protein selected from the group consisting of CD206, FOLR2, LGMN, CD204, CD163, and CD301; and ii) an IL-15 polypeptide.
 2. The fusion protein of claim 1, wherein the targeting unit is an antigen binding protein that specifically binds to said CD206.
 3. The fusion protein of claim 1, wherein the targeting unit is an antigen binding protein that specifically binds to FOLR2.
 4. The fusion protein of claim 1, wherein said antigen binding protein is selected from the group consisting of an immunoglobulin single variable domain and a single chain variable fragment (scFv).
 5. The fusion protein of claim 3, wherein said immunoglobulin single variable domain is a nanobody.
 6. The fusion protein of claim 5, wherein said nanobody binds to CD206.
 7. The fusion protein of claim 5, wherein said nanobody binds to FOLR2.
 8. The fusion protein of claim 1, wherein the targeting unit and the IL-15 polypeptide are connected by a linker.
 9. A nucleic acid encoding the fusion protein of claim
 1. 10. A host cell comprising the nucleic acid of claim
 9. 11. A method of inducing a cancer specific immune response, comprising: administering the fusion protein of claim 1 to a subject diagnosed with cancer under conditions such that said subject generates or amplifies an immune response to cancer cells in said subject. 